System and method for radioactive emission measurement

ABSTRACT

A method of radioactive-emission-measurement. The method comprises providing a camera for the detection of single emissions, which defines proximal and distal ends. The camera is configured for enabling a reconstruction of a volumetric image having a line spread function of less than 7 mm Full Width Half Maximum (FWHM) when given a substantially line source of radioactive emission, with an activity of 5 mCi, within a region-of-interest volume, at a distance of at least 100 mm from said distal end, with air being substantially the only operating medium. The method further comprises detecting at least 1 of every 5000 photons, emitted from at least one radioactive-emission source, located within a certain region-of-interest volume, using the camera, and reconstructing a volumetric radioactive-emission image from the detected photons.

RELATED APPLICATIONS

This application is a continuation-in-part of PCT Patent Application No.PCT/IL2005/001173 filed on Nov. 9, 2005 which is a continuation-in-partof PCT Patent Application Nos. PCT/IL2005/000572 and PCT/IL2005/000575filed on Jun. 1, 2005.

PCT Patent Application Nos. PCT/IL2005/000572 and PCT/IL2005/000575filed on Jun. 1, 2005 claim the benefit of U.S. Provisional PatentApplication Nos. 60/648,690 filed on Feb. 2, 2005; 60/648,385 filed onFeb. 1, 2005; 60/640,215 filed on Jan. 3, 2005; 60/636,088 filed on Dec.16, 2004; 60/635,630 filed on Dec. 14, 2004; 60/632,515 filed on Dec. 3,2004; 60/632,236 filed on Dec. 2, 2004; 60/630,561 filed on Nov. 26,2004 and 60/625,971 filed on Nov. 9, 2004.

PCT Patent Application No. PCT/IL2005/001173 filed on Nov. 9, 2005 alsoclaims the benefit of Israel Patent Application No. 171346 filed on Oct.10, 2005 and U.S. Provisional Patent Application Nos. 60/720,541 and60/720,652 filed on Sep. 27, 2005; 60/720,034 filed on Sep. 26, 2005;60/702,979 filed on Jul. 28, 2005; 60/700,753 filed on Jul. 20, 2005;60/700,752 filed on Jul. 20, 2005; 60/700,318 filed on Jul. 19, 2005;60/700,317 filed on Jul. 19, 2005; 60/700,299 filed on Jul. 19, 2005;60/691,780 filed on June, 2005; 60/675,892 filed on Apr. 29, 2005; andU.S. Provisional Patent Application No. 60/628,105 filed on Nov. 17,2004.

PCT Patent Application No. PCT/IL2005/001173 filed on Nov. 9, 2005 isalso a continuation-in-part of PCT Patent Application No.PCT/IL2005/000048 filed on Jan. 13, 2005.

This Application is also a continuation-in-part of PCT PatentApplication No. PCT/IL2006/000834 filed on Jul. 19, 2006, which claimsthe benefit of U.S. Provisional Patent Application No. 60/741,440 filedon Dec. 2, 2005.

This Application also claims the benefit of U.S. Provisional PatentApplication No. 60/800,845 filed on May 17, 2006.

The contents of the above Applications are incorporated herein byreference.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to nuclear imaging, and more particularly,to systems, methods, and cameras for radioactive-emission detection andmeasurements, without coincidence, with sensitivity which meets, andeven outperforms that of PET, in terms of speed and spatial resolution,and with a high spectral resolution not available in PET.

Radionuclide imaging aims at obtaining an image of a radioactivelylabeled substance, that is, a radiopharmaceutical, within the body,following administration, generally, by injection. The substance ischosen so as to be picked up by active pathologies to a different extentfrom the amount picked up by the surrounding, healthy tissue; inconsequence, the pathologies are operative as radioactive-emissionsources and may be detected by radioactive-emission imaging. A pathologymay appear as a concentrated source of high radiation, that is, a hotregion, as may be associated with a tumor, or as a region of low-levelradiation, which is nonetheless above the background level, as may beassociated with carcinoma.

A reversed situation is similarly possible. Dead tissue has practicallyno pick up of radiopharmaceuticals, and is thus operative as a coldregion.

The mechanism of localization of a radiopharmaceutical in a particularorgan of interest depends on various processes in the organ of interestsuch as antigen-antibody reactions, physical trapping of particles,receptor site binding, removal of intentionally damaged cells fromcirculation, and transport of a chemical species across a cell membraneand into the cell by a normally operative metabolic process. A summaryof the mechanisms of localization by radiopharmaceuticals is found inhttp://www.lunis.luc.edu/nucmed/tutorial/radpharm/i.htm.

The particular choice of a radionuclide for labeling antibodies dependsupon the chemistry of the labeling procedure and the isotope nuclearproperties, such as the number of gamma rays emitted, their respectiveenergies, the emission of other particles such as beta or positrons, theisotope half-life, and the decay scheme.

In PET imaging, positron emitting radio-isotopes are used for labeling,and the imaging camera detects coincidence photons, the gamma pair of0.511 Mev, traveling in opposite directions. Each coincident detectiondefines a line of sight, along which annihilation takes place. As such,PET imaging collects emission events, which occurred in an imaginarytubular section enclosed by the PET detectors. A gold standard for PETimaging is PET NH₃ rest myocardial perfusion imaging with N-13-ammonia(NH₃), at a dose level of 740 MBq, with attenuation correction. Yet,since the annihilation gamma is of 0.511 Mev, regardless of theradio-isotope, PET imaging does not provide spectral information, anddoes not differentiate between radio-isotopes.

In SPECT imaging, primarily gamma emitting radio-isotopes are used forlabeling, and the imaging camera is designed to detect the actual gammaemission, generally, in an energy range of approximately 11-511 KeV.Generally, each detecting unit, which represents a single image pixel,has a collimator that defines the solid angle from which radioactiveemission events may be detected.

Because PET imaging collects emission events, in the imaginary tubularsection enclosed by the PET detectors, while SPECT imaging is limited tothe solid collection angles defined by the collimators, generally, PETimaging has a higher sensitivity and spatial resolution than does SPECT.Therefore, the gold standard for spatial and time resolutions in nuclearimaging are defined for PET.

Radiopharmaceuticals are a powerful labeling tool, yet the radiationdose to the patients needs to be taken into account.

In the International System of units (SI), the becquerel (Bq) is theunit of radioactivity. One Bq is 1 disintegration per second (dps). Thecurie (Ci) is the old standard unit for measuring radioactivity of agiven radioactive sample and is equivalent to the activity of 1 gram ofradium, originally defined as the amount of material that produces3.7×10¹⁰ dps. Regarding dose levels applicable to radiopharmaceuticals,1 GBq=27 millicuries.

The rad is a unit of absorbed radiation dose in terms of the energydeposited in a living tissue, and is equal to an absorbed dose of 0.01joules of energy per kilogram of tissue.

The biologically effective dose in rems is the dose in rads multipliedby a “quality factor” which is an assessment of the effectiveness ofthat particular type and energy of radiation. Yet, for gamma and betarays, the quality factor is 1, and rad and rem are equal. For alphaparticles, the relative biological effectiveness (rem) may be as high as20, so that one rad is equivalent to 20 rems.

The recommended maximum doses of radiopharmaceuticals are 5 rems for awhole body dose and 15 rads per organ, while the allowable dose forchildren is one tenth of the adult level. The per-organ criterionprotects organs where accumulation takes place. For example,radiopharmaceuticals for which removal is primarily by the liver shouldbe administered at a lower dose than those for which removal is partlyby the liver and partly by the kidney, because in the former, a singleorgan is involved with the removal, and in the latter, there is sharingof the removal.

In order to minimize exposure to the tissue, radiopharmaceuticals, whichhave a long half life, and radiopharmaceuticals, which have radioactivedaughters, are generally avoided.

SUMMARY OF THE INVENTION

Radioimaging methods, devices and radiopharmaceuticals therefor.

The present invention relates to radioimaging cameras characterized byunprecedented high sensitivity allowing for high resolution imageaquizition for use in diagnostics; algorithms and systems operable inconjunction with the camera, the algorithms and systems include, but arenot limited to, predetermined view selection algorithm and system,active vision (on flight view selection) algorithm and system, closedloop administration of a radiopharmaceuticallgothim and system, expertsystem diagnostic algorithm and system, automatic dose preparationalgorithm and kinetic parameter extraction algorithm and system; lowdose radiopharmaceuticals; combinations of radiopharmaceuticals eitheras compositions (cocktails) and/or kits; an administering device ofradiopharmaceuticals, which may include syringes, pumps and IV lines;mixers for mixing different radiopharmaceuticals; and an ERP system forcontrolling and monitoring each one or more of the above.

The present invention emerges from the development of a radioimagingcamera characterized by unprecedented sensitivity. The sensitivity ofthe camera is attributed, as is further detailed hereinunder, to atleast the following constructual features: (a) a plurality of detectingunits; (b) movability of the detecting units one with respect to theother; (c) thus allowing concentrated focus on a region-of-interest bythe individual detecting units; and (d) wiring diagram with minimalmultiplexing, thereby preventing saturation thereof.

As a result of this sensitivity, it is now possible using the camera ofthe present invention to (a) detect low dose radiopharmaceuticals; (b)perform fast kinetic studies; (c) extract kinetic parameters for thedistribution of a radiopharmaceutical under different diagnostic setups,thereby allowing (i) formulating radiopharmaceuticals based on the newlyachieved knowledge of the kinetic parameters; (ii) diagnostics based onthe kinetic parameters; (iii) formulating new therapeutic drugs based onthe kinetic parameters; and (iv) using the kinetic parameters as aninput to the expert system for diagnostics; (d) provide images ofco-administered radiopharmaceuticals; and (e) allow diagnosticallymeaningful imaging at a far faster rate as compared to conventionalprior art radioimaging cameras.

In order to minimize the exposure of a testee to radioactive substancesand in order to maximize the diagnostic capabilities using radioimaging,the inventors of the present invention developed low dose preparationsof radiopharmaceuticals and compositions and kits comprising two or moreradiopharmaceuticals adapted for use in conjunction with the camera andall other aspects of the invention.

In another exemplary embodiment of the current invention, the

probe system includes multiple blocks of detectors positioned in astructure encircling the imaged area, each is able to rotate about alongitudinal axis substantially parallel to the main axis of thesubject.

In a further example case of 10 such blocks of detectors, each coveringa 40×160 mm section covering about 180-200 deg of the circle around theimaged area, with 10 blocks of collimators each covering 1024 pixelsarranged in a 16×64 pixel matrix, with square collimator opening of2.46×2.46 mm, and a length of 20 mm], the system demonstrated ability todetect about one out of 1500 of the emitted photons from a

2.7 mCi Co⁵⁷ point source that was moved about in a 40×30×15 cm volumefacing the probe.

When located in the center of the imaged area (about 150 mm from thedetectors), while the energy window for acquisition was about 5%, andthe detectors were sweeping a wide angular range.

In a further exemplary embodiment, substantially all detectors are ableto simultaneously image the region of interest containing the pointsource and thus obtaining one out of every 500 of the emitted photons.

It is known to the skilled in the art that further opening the energywindow of the detector to about 15%, enables acquisition of about oneout of 250 photons of the photons emission in an experimental settingsimilar to the previous example.

In a further example, each such detector having multiple pixels is ofabout 5 cm wide or more, thus producing a region of interest of at least5 cm in diameter, from which said sensitivity and said resolution isbeing obtained even without the need to move any of the detectors.

In a further possible embodiment of the present invention the width ofeach detector is about 10 cm wide, thus enabling regions of interest ofeven bigger diameters at said resolution and sensitivity with a smallerdetector motion such that bigger objects are continuously viewed by thedetector with only small angular detector motion.

In a further possible embodiment of the present invention the detectorsarray may encircle the imaged subject to the extent of 360 deg, forexample by having two hemi circles from both sides of the subject. Thesensitivity in such case is estimated be about 1 in 125.

In a further exemplary embodiment additional detectors may be positionedto obtain views not perpendicular to the subject's main longitudinalaxis, for example by upper view (e.g. from the shoulders) and abdominalview of the target region (in the case of cardiac mapping). It isestimated that such addition may increase the sensitivity but a factorof about ×2.

As a result, an example embodiment is estimated to be able to image avolume of about 5 cm diameter located about 150 mm from the detectors,with energy window of 15%, producing spatial resolution of about 5 mm inapproximately 100 sec, with a total sensitivity of about 1 photons beingdetected out of 65 emitted.

It will be recognized by a person skilled in the art that a system builtaround the principles as described by the examples and embodiments ofthe present invention can thus reach the sensitivity necessary to detectsubstantially more than one photon from every 100 emitted. This resultfor an imaging system provides more than 100 time better sensitivitythan commercially available cameras that have a sensitivity ranging fromsubstantially from 170 counts/microCurie/minute (or 1 photon in 8500photons emitted for a Low resolution low energy collimator to about 1photon in every 15000 emitted for a high resolution medium energycollimator), while maintaining similar energy windows, and potentiallysimilar or better resolution.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

In the drawings:

FIGS. 1A-1B schematically illustrate detecting units and blocks forradioactive emission detection;

FIG. 2 schematically illustrates the basic component of a system,comprising a radioactive-emission camera and a position-tracking device,both in communication with a data-processing system;

FIGS. 3A-3B schematically illustrate the manner of operating theradioactive-emission camera with the position-tracking device;

FIGS. 4A-4C schematically illustrate extracorporeal and intracorporealradioactive-emission camera operative with position-tracking devices;

FIGS. 5A-5F present the principles of modeling, for obtaining an optimalset of views, in accordance with embodiments of the present invention;

FIGS. 6A and 6B pictorially illustrate a view and viewing parametersassociated with it, in accordance with definitions of the presentinvention;

FIGS. 7A-7C schematically illustrate anatomical constraints, which areto be modeled, in accordance with embodiments of the present invention;

FIG. 8 illustrates, in flowchart form, a method of predefining a set ofviews for functional imaging, tailored for imaging a specific bodystructure, and optimized with respect to the functional informationgained about the body structure, in accordance with embodiments of thepresent invention;

FIGS. 9A-9F schematically illustrate possible models and collections ofviews, for a body structure, in accordance with embodiments of thepresent invention;

FIG. 10 illustrates, in flowchart form, a method of functional imaging,tailored for imaging from esophagus, and optimized with respect to thefunctional information gained about the body structure, in accordancewith embodiments of the present invention;

FIG. 11 schematically illustrates the process of modeling in twoiterations, for zooming in on a pathological feature, in accordance withembodiments of the present invention;

FIG. 12 illustrates, in flowchart form, a method of several iterationsfor zooming in on a pathological feature, when performing in vivomeasurements, in accordance with embodiments of the present invention;

FIGS. 13A-13E schematically illustrate possible camera designs, and theprocess of obtaining views based on a model and a camera design, inaccordance with embodiments of the present invention;

FIG. 14 illustrates, in flowchart form, a method of selecting a cameradesign optimized with respect to information gained about a bodystructure, in accordance with embodiments of the present invention;

FIG. 15 illustrates, in flowchart form, a method of selecting a cameradesign, based on the rate of data collection and other designconsiderations, in accordance with embodiments of the present invention;

FIGS. 16A-16L schematically illustrate viewing of an elliptical modeledvolume, by the radioactive-emission camera, in accordance withembodiments of the present invention;

FIGS. 17A-17N schematically illustrate various detecting units andblocks, which may be incorporated in camera designs, in accordance withembodiments of the present invention;

FIGS. 18A-18D schematically illustrate possible motions of aradioactive-emission camera, for a single detecting unit and a singleblock, in accordance with embodiments of the present invention;

FIGS. 19A-19E schematically illustrate other possible motions of aradioactive-emission camera, for a single block, in accordance withembodiments of the present invention;

FIGS. 20A-20H schematically illustrate possible motions of aradioactive-emission camera, having a plurality of pairs ofradioactive-emission blocks;

FIGS. 21A-21D schematically illustrate other possible motions of aradioactive-emission camera, having a plurality of pairs ofradioactive-emission blocks;

FIGS. 22A-22X schematically illustrate a radioactive-emission camerasystem, comprising a plurality of assemblies, motions of individualblocks, and characteristics of an optimal camera, in accordance withembodiments of the present invention;

FIG. 22Y-22AA schematically illustrate a center of viewing, for a givencamera design, in accordance with embodiments of the present invention;

FIGS. 23A-23D schematically illustrate a radioactive-emission camerasystem, in accordance with embodiments of the present invention;

FIGS. 24A-24C schematically illustrate the modeling of a prostate as aprocess of two iterations, for zooming in on a pathology, in accordancewith embodiments of the present invention;

FIGS. 25A-25E schematically illustrate the external appearance and theinternal structure of the radioactive-emission camera for the prostate,in accordance with an embodiment of the present invention;

FIG. 26 illustrates further the internal structure of theradioactive-emission camera for the prostate, in accordance with anembodiment of the present invention;

FIG. 27 schematically illustrates the radioactive-emission camera forthe prostate, integrated with an ultrasound camera, in accordance withanother embodiment of the present invention;

FIG. 28 schematically illustrates an ultrasound wave impinging on aprostate, in accordance with embodiments of the present invention;

FIGS. 29A-29C illustrate the co-registering of a radioactive-emissionimage and an ultrasound image, in accordance with embodiments of thepresent invention;

FIG. 30 schematically illustrates the radioactive-emission camera forthe prostate, integrated with a surgical needle, in accordance withanother embodiment of the present invention;

FIGS. 31 and 32 schematically illustrates the operation of the surgicalneedle of FIG. 30; and

FIG. 33 schematically illustrates the modeling of the femalereproductive system as a process of two iterations, for zooming in on apathology, in accordance with embodiments of the present invention;

FIGS. 34A-34R schematically illustrate the external appearance and theinternal structure of the radioactive-emission camera for the femalereproduction tract, in accordance with an embodiment of the presentinvention;

FIGS. 35A-35Q schematically illustrate the external appearance and theinternal structure of the radioactive-emission camera for the esophagus,in accordance with an embodiment of the present invention;

FIGS. 36A and 36B schematically illustrates body organs, including anesophagus.

FIGS. 37-39 schematically illustrate the modeling of the heart as aprocess of two iterations, in accordance with embodiments of the presentinvention;

FIGS. 40-45 schematically illustrate the basic components of a cardiaccamera system, in accordance with an embodiment of the presentinvention;

FIG. 46 schematically illustrates the external appearance of aradioactive-emission-camera system for the heart, in accordance with anembodiment of the present invention;

FIGS. 47 and 48 schematically illustrate the internal structure of theradioactive-emission camera for the heart, in accordance with anembodiment of the present invention;

FIGS. 49A and 49B schematically illustrate the internal structure of theradioactive-emission camera for the heart, in accordance with anembodiment of the present invention;

FIG. 50 schematically illustrates the construction of radiationdetection blocks, in accordance with an embodiment of the presentinvention;

FIG. 51 schematically illustrates a cardiac model, in accordance with anembodiment of the present invention;

FIGS. 52A-52E schematically illustrate radiation detection blocksarranged for viewing a cardiac model, in accordance with an embodimentof the present invention;

FIG. 53 schematically illustrates a dual imaging system forradioactive-emissions in tandem with a three-dimensional structuralimager, in accordance with an embodiment of the present invention;

FIG. 54 schematically illustrates a dual imaging system forradioactive-emissions in tandem with a three-dimensional structuralimager, in accordance with an embodiment of the present invention;

FIGS. 55A-55C schematically illustrate the internal structure of theradioactive-emission camera for the dual imaging system, in accordancewith an embodiment of the present invention;

FIGS. 56A-56B schematically illustrate the internal structure of theradioactive-emission camera for the dual imaging system, in accordancewith an embodiment of the present invention;

FIGS. 57A-57B schematically illustrate a cranial model, in accordancewith an embodiment of the present invention;

FIG. 58 schematically illustrates a cranial model, in accordance with anembodiment of the present invention;

FIGS. 59A-59C schematically illustrate an imaging system forradioactive-emissions of the head, in accordance with an embodiment ofthe present invention;

FIGS. 60A-60K schematically illustrate the internal structure of theradioactive-emission camera for the head, in accordance with anembodiment of the present invention;

FIGS. 61A and 61B schematically illustrate a breast model, in accordancewith an embodiment of the present invention;

FIGS. 62A-62C schematically illustrate an imaging system forradioactive-emissions of the breast, in accordance with an embodiment ofthe present invention;

FIGS. 63A-63E schematically illustrate an imaging camera forradioactive-emissions of the breast, in accordance with an embodiment ofthe present invention;

FIGS. 64A-64K schematically illustrate an imaging system forradioactive-emissions of the breast, in accordance with an embodiment ofthe present invention;

FIGS. 64L-64M illustrates, in flowchart form, a method of examining abreast, in accordance with embodiments of the present invention;

FIGS. 65A-65C schematically illustrate an imaging camera forradioactive-emissions of the breast, in accordance with an embodiment ofthe present invention;

FIGS. 66A-66G schematically illustrate an imaging system forradioactive-emissions of the breast, in accordance with an embodiment ofthe present invention;

FIGS. 67A-67B schematically illustrate effect of distance on detectionefficiency of a radiation detector;

FIGS. 68A-68D schematically illustrate effect of distance on resolutionof a radiation detector;

FIGS. 69A-69D schematically illustrate “wasteful viewing” by an array ofradiation detectors;

FIGS. 70A-70C describe experimental results with grid point sources.

FIG. 71 schematically illustrates a non-wasteful radiation detectorarray, in accordance with an embodiment of the present invention;

FIGS. 72A-72E schematically illustrate non-wasteful radiation detectorarrays, in accordance with an embodiment of the present invention;

FIGS. 73A and 73B schematically illustrate non-wasteful radiationdetector arrays, in accordance with an embodiment of the presentinvention;

FIGS. 74A and 74B schematically illustrate the use of a non-wastefulradiation detector array, in accordance with an embodiment of thepresent invention;

FIGS. 75A and 75B illustrate Teboroxime physiological behavior,according to Garcia et al. (Am. J. Cardiol. 51^(st) Annual ScientificSession, 2002).

FIGS. 76A-80D schematically illustrate experimental data with the cameraof the present invention.

FIG. 81 is a description of advantageous and disadvantageous viewingpositions according to embodiments of the present invention.

FIG. 82 is a simplified flowchart of a method of performingradioactive-emission measurements of a body structure, according to apreferred embodiment of the present invention.

FIG. 83 shows an object shaped as a cylinder with a front protrusion,and having a high-remittance portion (hotspot).

FIG. 84 a illustrates an object having two high-emission regions ofinterest.

FIG. 84 b illustrates the added information provided by each of viewsV_(A) to V_(F).

FIGS. 85 a and 85 b are simplified flowcharts of iterative methods ofperforming radioactive-emission measurements of a body structure,according to a first and a second preferred embodiment of the presentinvention.

FIGS. 86 a and 86 b are simplified flowcharts of methods for dynamicallydefining further views, according to a first and a second preferredembodiment of the present invention.

FIG. 87 is a simplified flowchart of an iterative method for selectingfurther views, according to a preferred embodiment of the presentinvention.

FIG. 88 is a simplified flowchart of a single iteration of a viewselection method, according to a preferred embodiment of the presentinvention.

FIG. 89 is a simplified flowchart of a method for dynamically definingfurther views, according to a third preferred embodiment of the presentinvention.

FIG. 90 is a simplified block diagram of measurement unit for performingradioactive-emission measurements of a body structure, according to apreferred embodiment of the present invention.

FIG. 91 is a simplified flowchart of a method for measuring kineticparameters of a radiopharmaceutical in a body, according to a preferredembodiment of the present invention.

FIG. 92 is a schematic representation of a dynamic model of a voxel,according to a first preferred embodiment of the present invention.

FIG. 93 is a schematic representation of a dynamic model of a voxel,according to a second preferred embodiment of the present invention.

FIG. 94 is a schematic representation of a dynamic model of a voxel,according to a third preferred embodiment of the present invention.

FIG. 95 is a circuit diagram of a series RLC electronic circuit.

FIG. 96 is a simplified flowchart of a method for measuring kineticparameters of a radiopharmaceutical in an organ of a body, according toa preferred embodiment of the present invention.

FIG. 97 is a simplified flowchart of a process for obtaining the drugformulation, according to a preferred embodiment of the presentinvention.

FIG. 98 is a simplified flowchart of a method of radiopharmaceuticaladministration and imaging, according to a first preferred embodiment ofthe present invention.

FIG. 99 is a simplified flowchart of a method of radiopharmaceuticaladministration and imaging, according to a second preferred embodimentof the present invention.

FIG. 100 is a simplified block diagram of a radiopharmaceuticalmanagement system, according to a preferred embodiment of the presentinvention.

FIG. 101 is a simplified block diagram of an exemplary embodiment of aradiopharmaceutical handling module.

FIG. 102 is a block diagram of an exemplary embodiment of an imagingmodule.

FIG. 103 is a simplified illustrative diagram of a single-reservoircontrollable syringe.

FIG. 104 is a simplified illustrative diagram of a multiple-reservoircontrollable syringe.

FIG. 105 is a simplified illustrative diagram of an administrationdevice for controlled injection of multiple substances into a patientunder the supervision of an imaging module, according to a preferredembodiment of the present invention.

FIG. 106 is a simplified block diagram of a dose preparation system,according to a preferred embodiment of the present invention.

FIG. 107 is a simplified flow chart, illustrating a process for imaginga patient using multiple kinetic parameters and measuring the distancebetween respective kinetic parameters, to relate the patient orindividual voxels or groups of voxels to existing groups, thereby toarrive at a decision, regarding the patient or individual voxels orgroups of voxels, according to embodiments of the present invention.

FIG. 108 illustrates dynamic behavior of a parameter;

FIG. 109A-D illustrate different behaviors over time of differentkinetic parameters.

FIG. 110A illustrates dynamic behavior of an absorption parameter with adead or diseased membrane, and,

FIG. 110B illustrates the dynamic behavior of the same parameter with ahealthy membrane.

FIGS. 111A and 111B are of cardiac electrical cycles;

FIGS. 112A and 112B are of cardiac and respiratory gating in accordancewith a first embodiment, in accordance with embodiments of the presentinvention;

FIGS. 113A-113C are of cardiac and respiratory gating in accordance witha first embodiment, in accordance with embodiments of the presentinvention;

FIGS. 114A, 114B and 114C are of typical cardiac volumes and pressures,superimposed against the ECG tracing of FIG. 1B and the time scale 10 ofFIG. 3A, in accordance with embodiments of the present invention;

FIG. 115 is a graph of cardiac volume versus pressure over time andexemplary volumetric images, in accordance with embodiments of thepresent invention;

FIG. 116 is of a cardiac probe, in accordance with embodiments of thepresent invention.

FIG. 117 is a flowchart diagram of a method for calibrating aradiological imaging system by detecting radiation from one or morecalibration sources, according to various exemplary embodiments of theinvention.

FIG. 118 is a flowchart diagram of a method for calibrating aradiological imaging system by detecting radiation from one or moreradiopharmaceuticals, according to various exemplary embodiments of theinvention.

FIG. 119 is a schematic illustration of a device for calibrating aradiological imaging system, according to various exemplary embodimentsof the invention.

FIG. 120 is a schematic illustration of a device for administeringradiopharmaceuticals to a subject, according to various exemplaryembodiments of the invention.

FIGS. 121 a-e are schematic illustrations of a system for generating athree-dimensional image of a target region of a subject, according tovarious exemplary embodiments of the invention.

FIG. 122 is a flowchart diagram of a method for constructing athree-dimensional image of a target region of a subject, according tovarious exemplary embodiments of the invention.

FIG. 123 is a flowchart diagram of a method for constructing aradiological image of a target region of a subject, according to variousexemplary embodiments of the invention.

FIG. 124 is a flowchart diagram of a method for calculating intensityattenuation of a radiological image, according to various exemplaryembodiments of the invention.

FIG. 125 is a schematic diagram of a configuration for acquiring and/orusing multi-parametric information, in accordance with an exemplaryembodiment of the invention;

FIG. 126 is a flowchart of a method of acquiring and/or usingmulti-parametric information, in accordance with an exemplary embodimentof the invention;

FIG. 127 is a simplified space indicating a diagnosis and a normalphysiological state, in accordance with an exemplary embodiment of theinvention;

FIG. 128 shows a simplified two dimensional space showing a complexdiagnosis, in accordance with an exemplary embodiment of the invention.

FIG. 129 is a simplified diagram showing a single detector detectingfrom a target region;

FIG. 130 is a simplified diagram showing two detector positions (notnecessarily simultaneously) allowing three-dimensional information to beobtained from a target region;

FIGS. 131A-131D show a series of four time absorption characteristicsfor different radiopharmaceuticals within different tissues;

FIG. 132 is a simplified schematic diagram showing a device for drivingan imaging head and allowing control of the imaging head by the imageanalyzer device;

FIG. 133 is a simplified flow chart illustrating the image analysisprocess carried out by the analyzer in FIG. 132 in the case of a singlemarker;

FIGS. 134A-134D illustrate two sets of successive images of the sametarget area taken using two different markers respectively, according toa preferred embodiment of the present invention;

FIG. 135A is a simplified flow chart illustrating a procedure accordingto a preferred embodiment of the present invention using two or moremarkers for firstly identifying an organ and secondly determining thepresence or otherwise of a pathology within that organ;

FIG. 135B is a simplified flow chart showing a generalization of FIG.135A for the general case of two specific patterns;

FIG. 136 is a simplified flow chart illustrating a procedure accordingto a preferred embodiment of the present invention using two or moremarkers for identifying a region of low emissivity within a target areaand using that identification to control imaging resources to betterimage the identified region;

FIGS. 137A-137D illustrate two sets of successive images of the sametarget area taken using two different markers, in a similar way to thatshown in FIG. 134, except that this time the regions of interest are oneinside the other; and

FIG. 138 illustrates differential diagnosis using simultaneous imagingof two different radiopharmaceuticals.

FIGS. 139A-B is a table illustrating various radiopharmaceuticalcombinations and their uses in nuclear imaging.

FIG. 140 is a flowchart for imaging two isotopes that provideinappropriate cross talk, in accordance with embodiments of the presentinvention;

FIG. 141 schematically represents a time line for myocardial perfusion,in accordance with embodiments of the present invention; and

FIGS. 142 a-142C schematically illustrate photopeaks of Tc^(99m), Tl²⁰¹,and cross talk of Tc^(99m) at the Tl²⁰¹ energy window.

FIG. 143 is a camera electrical diagram showing an electronic blockdiagram indicating the high limits of the system. In this case,basically, the monolithic crystal of camera is divided to 40×2 blockseach of which is not affecting the others. In the conventionalcamera-every photon paralyzes the camera until cleared.

FIG. 144 describes a decay curve of Mo-99 to Tc-99m and to Tc-99;

FIG. 145 describes the build up of Tc-99m and Tc-99 with the decay ofMo-99.

FIG. 146 describes a standard elution curve;

FIG. 147 describes a recommended low-dose elution curve.

FIGS. 148A-V are tables describing protocols according to embodiments ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to radioimaging cameras characterized byunprecedented high sensitivity allowing for high resolution imageacquisition for use in diagnostics; algorithms and systems operable inconjunction with the camera, the algorithms and systems include, but arenot limited to, predetermined view selection algorithm and system,active vision (on the fly view selection) algorithm and system, closedloop administration of a radiopharmaceutical algorithm and system,expert system diagnostic algorithm and system, automatic dosepreparation algorithm and kinetic parameter extraction algorithm andsystem; low dose radiopharmaceuticals; combinations ofradiopharmaceuticals either as compositions (cocktails) and/or kits; anadministering device of radiopharmaceuticals, which may includesyringes, pumps and IV lines; mixers for mixing differentradiopharmaceuticals; and an ERP system for controlling and monitoringeach one or more of the above.

The present invention emerges from the development of a radioimagingcamera characterized by unprecedented sensitivity. The sensitivity ofthe camera is attributed, as is further detailed hereinbelow, to atleast the following constructual features: (a) a plurality of detectingunits; (b) movability of the detecting units one with respect to theother; (c) thus allowing concentrated focus on a region-of-interest bythe individual detecting units; and (d) wiring diagram with minimalmultiplexing, thereby preventing saturation thereof.

As a result of this sensitivity, it is now possible using the camera ofthe present invention to (a) detect low dose radiopharmaceuticals; (b)perform fast kinetic studies; (c) extract kinetic parameters for thedistribution of a radiopharmaceutical under different diagnostic setups,thereby allowing (i) formulating radiopharmaceuticals based on the newlyachieved knowledge of the kinetic parameters; (ii) diagnostics based onthe kinetic parameters; (iii) formulating new therapeutic drugs based onthe kinetic parameters; and (iv) using the kinetic parameters as aninput to the expert system for diagnostics; (d) provide images ofco-administered radiopharmaceuticals; and (e) allow diagnosticallymeaningful imaging at a far faster rate as compared to conventionalprior art radioimaging cameras.

In order to minimize the exposure of a subject to radioactive substancesand in order to maximize the diagnostic capabilities using radioimaging,the inventors of the present invention developed low dose preparationsof radiopharmaceuticals and compositions and kits comprising two or moreradiopharmaceuticals adapted for use in conjunction with the camera andall other aspects of the invention.

The principles and operation of the present invention may be betterunderstood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

Basic Imaging Concept

FIGS. 1A and 1B schematically illustrate a detecting unit 12 and a block90 of detecting units 12, respectively.

As seen in FIG. 1A, the detecting unit 12 is formed of a single-pixeldetector 91, having a thickness τ_(d) and a diameter D or, in the caseof a non-circular detector, a diameter equivalent. Alternatively,several pixels may be summed up so as to operate, in effect, as a singlepixel. Both the detector diameter D and the detector thickness τ_(d)affect the detecting efficiency. The detector diameter D determines thesurface area on which radioactive emission impinges; the greater thesurface area, the greater the efficiency. The detector thickness τ_(d)affects the stopping power of the detector. High-energy gamma rays maygo through a thin detector; the probability of their detection increaseswith an increase in the detector thickness τ_(d).

FIG. 1A illustrates a single-pixel detector 91, which by itself cannotgenerate an image; rather, all counts are distributed over the surfacearea of the detector 91.

As seen in FIG. 1B, the block 90 includes a plurality of the detectingunit 12, formed by dividing the detector 91 into a plurality ofelectrically insulated pixels 106, each associated with a collimator 96.The collimators 96 are of the diameter or diameter equivalent D, alength L, and a septum thickness τ. The collimators 96 may be, forexample, of lead, tungsten or another material which substantiallyblocks gamma and beta rays. The collimators 96 may be shaped as tubes,rectangular grids, or grids of any other polygon. Wide-angle ornarrow-angle collimators are also possible.

The collimator's geometry and specifically, the ratio of D/L, providesthe detecting unit 12 with a collection solid angle δ analogous to theviewing solid angle of an optical camera. The collection solid angle δlimits the radioactive-emission detection to substantially only thatradioactive emission which impinges on the detector 91 after passingthrough a “corridor” of the collimator 96 (although in practice, somehigh-energy gamma rays may penetrate the collimator's walls). With nocollimator, the collection angle δ, is essentially a solid angle of 4πsteradians.

Thus, the collimator's geometry affects both the detection efficiencyand the image resolution, which are defined as follows:

i. The detection efficiency is the ratio of measured radiation toemitted radiation; and

ii. The image resolution is the capability of making distinguishableclosely adjacent manifestations of a pathology, or the capability toaccurately determine the size and shape of individual manifestations ofa pathology.

While it is naturally desired to optimize both the detection efficiencyand the image resolution, they are inversely related to each other. Thedetection efficiency increases with an increase in the collimatorcollection angle, and the image resolution decreases with an increase inthe collimator collection angle.

In other words, while a wide-aperture, single-pixel detecting unit, suchas that of FIG. 1A provides high efficiency, it does not lend itself tothe generation of a two-dimensional image, and the wide aperture blursthe information regarding the direction from which the radiation isemitted. Yet as the resolution is increased, for example, in thedetecting unit 12 of FIG. 1B, the detection efficiency decreases.

Commonly owned US Applications 20040015075 and 20040054248 and commonlyowned PCT publication WO2004/042546, all of whose disclosures areincorporated herein by reference, describe systems and methods forscanning a radioactive-emission source with a radioactive-emissioncamera of a wide-aperture collimator and, at the same time, monitoringthe position of the radioactive-emission camera, at very fine timeintervals, to obtain the equivalence of fine-aperture collimation. Inconsequence, high-efficiency, high-resolution images of a radioactivityemitting source are obtained. This is discussed below with regard toFIGS. 2-3B.

FIG. 2 schematically illustrates the basic component of a system 120comprising a radioactive-emission camera 122, operative as a detectionsystem, and a position-tracking device 124, both in communication with adata-processing system 126. The radioactive-emission camera 122 isassociated with a first coordinate system 128, and the position-trackingdevice 124 is associated with a second coordinate system 128′, whereinthe position-tracking device 124 monitors the position of theradioactive-emission camera 122 as a function of time. Thedata-processing system 126 processes the measurements of both theradioactive-emission camera 122 and the position-tracking device 124 andcombines them to form the image.

FIG. 3A schematically illustrates a manner of operating theradioactive-emission camera 122 with the position-tracking device 124 ofthe system 120. The radioactive-emission camera 122 moves about an areaof radioactive emission 110, for example, in the direction of an arrow118, so as to measure a radioactive emission distribution 112, as afunction of time, while the position-tracking device 124 monitors theposition of the camera 122. The radioactive-emission camera 122 may be asingle-pixel detector of high efficiency, which is incapable, by itself,of producing images. Nonetheless, a data-processing system 126 processesa radioactive-count-rate input 121 together with a position-trackinginput 123, using algorithms 125, to reconstruct an image 110′ of thearea of radioactive emission 110 for example, on a display unit 129.

Imaging according to this concept is illustrated in FIG. 3B. The area ofradioactive emission 110 is located in a two-dimensional coordinatesystem u;v, and includes two hot points 115. The camera 122 moves from aposition P(1), at a time t(1), to a position P(2), at a time t(2), whilemeasuring the radioactive emission distribution 112 of the area ofradioactive emission 110, including the hot points 115.

An example of a suitable position-tracking device 124 for use withsystem 120 is the miniBird™, which is a magnetic tracking and locationsystem commercially available from Ascension Technology Corporation,P.O. Box 527, Burlington, Vt. 05402 USA(http://www.ascension-tech.com/graphic.htm). The miniBird™ measures thereal-time position and orientation (in six degrees of freedom) of one ormore miniaturized sensors, so as to accurately track the spatiallocation of cameras, instruments, and other devices. The dimensions ofthe miniBird™ are 18 mm×8 mm×8 mm for the Model 800 and 10 mm×5 mm×5 mmthe Model 500. Alternatively, other optical tracking systems which maybe used are NDI-POLARIS of Northern Digital Inc., Ontario, Canada, whichprovides passive or active systems, a magnetic tracking device ofNDI-AURORA, an infrared tracking device of E-PEN system, or anultrasonic tracking device of E-PEN system. Additionally oralternatively, the position-tracking device may be an articulated-armposition-tracking device, an accelerometer-based position-trackingdevice, a potentiometer-based position-tracking device, or aradio-frequency-based position-tracking device.

Commonly owned US application 20040054248 and commonly owned PCTpublication WO2004/042546 further disclose various extracorporeal andintracorporeal systems 120 wherein the position-tracking devices 124associated with the radioactive-emission cameras 122 have relativelywide apertures. Examples of extracorporeal and intracorporealradioactive-emission cameras of this type are seen in FIGS. 4A-4C.

FIG. 4A schematically illustrates one embodiment of system 120,including a hand-held, extracorporeal device 170, which includes thecamera 122, having a detector 132 and a collimator 134. The system 120also includes a controller 130 and a position-tracking device 124,wherein the camera 122 and the position-tracking device 124 areassociated with the data-processing system 126 discussed above withreference to FIGS. 2-3B.

FIG. 4B schematically illustrates another embodiment of system 120wherein an intracorporeal camera device 180 includes theradioactive-emission camera 122 mounted on a catheter 136. The camera122 includes the detector 132, the collimator 134, and theposition-tracking device 124, wherein the camera 122 and the positiontracking device 124 are associated with the data-processing system 126discussed above with reference to FIGS. 2-3B. The camera 122 isconfigured so as to penetrate a tissue 135, via a Trocar valve 138. Astructural imager 137, such as an ultrasound imager or an MRI camera mayfurther be included.

FIG. 4C schematically illustrates yet another embodiment of systemwherein an intracorporeal camera device 190 is adapted for rectalinsertion. The device 190 includes the radioactive-emission camera 122,which includes a plurality of the detectors 132 and the collimators 134associated with the position-tracking device 124. The intracorporeal 190device may be further adapted for motion along the x and ω directions.For example, the intracorporeal device 190 may include a motor 154 formoving the device 190 in the x and ω directions, such that, onceinserted into a rectum, it may be propelled therealong. A suitable motor154 may be obtained, for example, from B-K Medical A/S, of Gentofte, DK,and may be adapted to transmit information to the data-processing system126, regarding the exact position and orientation of the intracorporealdevice 190. In some embodiments, the motor 154 may be used in place ofthe position-tracking device 124. Alternatively, it may be used inaddition thereto. The intracorporeal device 190 may further include thestructural imager 137, such as an ultrasound imager or an MRI.

Initial View Determination

Predetermined Views, Based on a Model of a Body Structure

Definition of a View

Referring now to the drawings, FIGS. 5A-5F present the principles ofmodeling, for obtaining an optimal set of views, in accordance withembodiments of the present invention.

FIG. 5A schematically illustrates a body section 230 having aregion-of-interest (ROI) 200. The region-of-interest 200 may beassociated with a body structure 215 having a specificradioactive-emission-density distribution, possibly suggestive of apathological feature, this feature termed herein organ target 213.Additionally, there may be certain physical viewing constraintsassociated with the region-of-interest 200.

In accordance with embodiments of the present invention, FIG. 5Cillustrates, in flowchart form, a method 205 for best identifying anoptimal and permissible set of views for measuring theradioactive-emissions of the region-of-interest 200, such that athree-dimensional image thereof may be reconstructed. The method 205includes the following steps:

in a box 206: modeling the region-of-interest 200 as a model 250 of avolume U, wherein U is the region-of-interest volume, and wherein thevolume U may include one or several radioactive-emission sources,operative as modeled organ targets HS located within anatomicalconstraints AC, as seen in FIG. 5B;

in a box 207: obtaining an optimal and permissible set of views for themodeled volume U FIG. 5B; and

in a box 208: applying the optimal set of views to the in-vivoregion-of-interest 200 and the body structure 215 of FIG. 5A.

It will be appreciated that the model 250 of the region-of-interest 200may be based on general medical information of the body structure 215and common pathological features associated with it. Additionally, themodel may be based on information related to a specific patient, such asage, sex, weight, and body type. Furthermore, in order to facilitategeneration of the model 250, a structural image, such as by ultrasoundor MRI, may be used for providing information about the size andlocation of the body structure 215 in relation to the body section 230.

FIGS. 5D-5F schematically illustrate three types of the modeled organtargets HS, as follows:

i. a region of concentrated radiation, or a hot region, for example, asmay be associated with a malignant tumor and as seen in FIG. 5D;

ii. a region of low-level radiation, which is nonetheless abovebackground level, for example, as may be associated with carcinoma andas seen in FIG. 5E; and

iii. a region of little radiation, or a cold region, below thebackground level, for example, as may be associated with dead tissue andas seen in FIG. 5F.

Referring further to the drawings, FIGS. 6A and 6B pictoriallyillustrate a view and viewing parameters associated therewith, inaccordance with embodiments of the present invention.

FIG. 6A illustrates the volume U, subdivided into voxels u. The volume Uis defined in a six-degree coordinate system x;y;z;ω;θ;ρ having a pointof origin P0(x0; y0; z0; ω0; θ0; ρ0). A detecting unit 102 is positionedat a location and orientation P1(x1; y1; z1; ω1; θ1; ρ1). The detectingunit 102 has a detector 104, formed of a specific detector materialhaving a thickness τ_(d), and a collimator 108, having a diameter D anda length L and defining a collection angle δ.

FIG. 6B schematically illustrates the emission rate of the volume U, asa function of time, given that a radioactive material of a specifichalf-life has been administered at a time T0.

A view may thus be defined as a group of nonzero probabilities ofdetecting a radioactive emission associated with all the voxels thatform a sector S (FIG. 6A). A view is sometimes referred to as aprojection, and the two terms are synonymous. Furthermore, a viewdefined over a sector S can be naturally extended to be defined over theset of all voxels, by simply associating a zero probability with everyvoxel outside the sector S. This makes possible the application ofmathematical operations over the entire volume U.

A view is dependent on the following viewing parameters:

Location and Orientation Parameters:

The location and orientation of the detecting unit 12 in asix-dimensional space, P1(x1; y1; z1; ω1; θ1; ρ1), with respect to theorigin P0(x0; y0; z0; ω0; θ0; ρ0) of the volume U.

Detecting-Unit Parameters:

The collection angle δ which, together with the location and orientationparameters P1(x1; y1; z1; ω1; θ1; ρ1) with respect to the origin P0(x0;y0; z0; ω0; θ0; ρ0), define the sector S;

The detector material, which affects the detector efficiency;

The detector thickness τ_(d), which affects the detector's stoppingpower, hence, its efficiency; and

The diameter of the detecting unit, or the effective diameter,calculated so as to produce a circle of the same area, when the geometryis not a circle.

Attenuation Parameters:

Attenuation properties of all the voxels within the sector S, as theyaffect the probabilities that radioactive emissions from a specificvoxel will reach the detector, wherein different voxels within thesector S may have different attenuation properties, since several typesof tissue may be involved.

Radiopharmaceutical Parameters:

The half life t_(1/2) of the radiopharmaceutical, the types ofradioactive emission, whether gamma or beta, and the energies of theradioactive emissions, which affect the probability of detection.

As used herein the phrase “kinetic profile” means a collection of one ormore parameters describing the rate of distribution due to flow, uptake,bioclearance, diffusion, active transport, metabolism and the like.

A kinetic profile is either definable in general or per patient, perorgan, per tissue and under various conditions, such as pathologies andstimulations.

Time Parameters:

T0 is the time of administrating the radiopharmaceutical, T1 is the timesince administration, and the duration of the measurement is ΔT1, whichaffects the number of emissions that occur during theradioactive-emission measurement.

Some of these viewing parameters are fixed for a particular situation.Specifically, the tissue attenuation parameters are given. Additionally,the time T1 since administration of the radiopharmaceutical is generallygoverned by the blood pool radioactivity, since it is generallynecessary to wait until the blood pool radioactivity dies out forlow-level detection to be possible. For the remaining viewingparameters, optimization may be carried out.

The remaining viewing parameters may be divided into two categories:

i. viewing parameters in the design of a radioactive-emission camera;

ii. viewing parameters for an optimal set of views, for a given camera.

Viewing Parameters for an Optimal Set of Views, for a Given Camera

Referring further to the drawings, FIGS. 7A-7C schematically illustrateanatomical constraints, which may hinder measurements.

FIG. 7A schematically illustrates the region-of-interest 200, for whicha three-dimensional radioactive-emission image is desired. Theregion-of-interest 200 is in free space, with no constraints to limitaccessibility to it. Thus, a radioactive-emission camera 210 may travel,for example, along tracks 202 and 204, and any other track, unhindered.

In FIG. 7B, the region-of-interest 200 is associated with the bodystructure 215, such as a prostrate, in vivo. For obtaining aradioactive-emission image, the radioactive-emission camera 210 may beinserted transrectally, so as to travel in a rectum 206, for example, inthe direction of an arrow 208. Its ability to image the prostrate islimited by anatomical constraints.

In FIG. 7C, the region-of-interest 200 is associated with the bodystructure 215, such as a heart, a breast, or another organ, in vivo, andthe radioactive-emission camera 210 may be an extracorporeal camera,which may perform radioactive-emission measurements from outside thebody, on an extracorporeal surface 214, for example when moving along atrack 212.

In each of these cases, it is desired that a reconstructedthree-dimensional radioactive-emission image of the region-of-interest200 be obtained at a predetermined quality. This is achieved bypredefining an optimal set of radioactive-emission measurement views,tailored to the specific body structure 215 and optimized with respectto the information gained regarding the body structure 215.

Referring further to the drawings, FIG. 8 illustrates, in flowchartform, a method 300 of predefining a set of views for functional imaging,tailored for imaging a specific body structure, and optimized withrespect to the functional information gained about the body structure,in accordance with embodiments of the present invention. In effect, FIG.8 is an expansion of FIG. 5C. The method 300 comprises:

in a box 302: providing a model of the body structure 215, based on itsgeometry;

in a box 304: providing a model of anatomical constraints, which limitaccessibility to the body structure;

in a box 306: providing a collection of views of the modeled bodystructure obtained within the modeled anatomical constraints;

in a box 308: providing a scoring function, by which any set of at leastone view, from a collection of views, is scorable with a score thatrates information obtained from the modeled body structure by the set;

in a box 310: forming sets of views from the collection of views andscoring them with the scoring function; and

in a box 312: selecting a set of views, from the collection of views,based on their scores, as the predefined set of views.

The model of the body structure is based on anatomical knowledgeregarding its size, shape, and weight. In fact, different models may beprovided, for example, for different ages, sexes, weights, and bodytypes, such as heavy-built, medium-built, or small-built. In accordancewith a first embodiment, the body structure is modeled assuming thatthere is no radioactive emission throughout its volume. In accordancewith other embodiments, the body structure may be modeled with one ormore modeled organ targets, simulating different pathological features.Specifically, the modeled organ targets may be hot regions, of aradioactive-emission intensity higher than the background level, regionsof low-level radioactive-emission intensity, which is nonetheless abovethe background level, and cold regions, of a radioactive-emissionintensity lower than the background level. These may be distributed inaccordance with medical records, which teach of sites within the bodystructure that may be more susceptible to certain pathologies.

Similarly, the model of anatomical constraints which limit accessibilityto the body structure is based on anatomical knowledge, and differentmodels may be provided, for example, for different ages, sexes, weights,and body types.

The collection of views may be obtained by several methods. It may becalculated analytically for the modeled body, based on the viewparameters. Additionally or alternatively, computer simulations of themodeled body and the view parameters may provide the collection ofviews. Additionally or alternatively, measurements may be performedusing a point source and a detecting unit of appropriate parameters, atdifferent locations and orientations of the detecting unit, so as tosimulate the desired geometries.

It will be appreciated that a combination of these may be used. Forexample, the measurements may be performed in air, but correctedanalytically or by computer simulations, for tissue attenuation.

Referring further to the drawings, FIGS. 9A-9F schematically illustratepossible models and collections of views for a body structure, inaccordance with embodiments of the present invention.

FIG. 9A schematically illustrates four views, formed by sectors S1, S2,S3, and S4 through the volume U, which has an even distribution ofradioactive emission.

FIG. 9B schematically illustrates three views, formed by sectors S1, S2,and S3, through the volume U, which includes a modeled pathologicalfeature, which is the modeled organ target, HS.

FIG. 9C schematically illustrates three views, formed by sectors S1, S2,and S3 through the volume U, which includes a modeled organ target, HS′,of the same type as that of the modeled organ target HS, (that is,either a hot region or a cold region) but somewhat displaced along thex;y;z coordinate system. Additionally, the modeled organ target HS ofFIG. 9B is superimposed in FIG. 9C, for illustrative purposes, in orderto show the displacement, delta1, of modeled organ target HS′ frommodeled organ target HS.

FIG. 9D schematically illustrates three views, formed by sectors S1, S2,and S3 through the volume U, which includes a modeled organ target, HS″,of the same type as that of the modeled organ targets HS and HS′, butsomewhat displaced along the x;y;z coordinate system from them.Additionally, the modeled organ targets HS of FIG. 9B and HS′ of FIG. 9Care superimposed in FIG. 9D, for illustrative purposes, in order to showthe displacements delta2 and delta3, vis a vis HS″ of FIG. 9D.

FIG. 9E schematically illustrates three views, formed by sectors S1, S2,and S3 through the volume U, which includes two modeled organ targets,HS1 and HS2.

FIG. 9F schematically illustrates four possible models of organs, shownas elliptical volumes, each with a slightly different distribution ofmodeled organ targets.

The modeled organ targets may be termed emmitance models. In general, anemmitance model is based on a particular radiopharmaceutical, whichfixes both the rate of emission and the change in the rate of emissionwith time, determining the difference between the modeled organ targetand the background level, as a function of time. To study the effect ofdifferent radiopharmaceuticals on the views, one may provide differentemmitance models, based on different radiopharmaceuticals and differentelapsed times relative to their administration.

The choice of an optimal set of views from among a collection of views,such as any of those illustrated in FIGS. 9A-9E, is based on a scoringfunction, which rates different sets of views in terms of theirinformation regarding the volume U. The scoring function is based oninformation theoretic measures that rate the quality of the data whicheach set of views provides.

Information Theoretic Measures

A brief description of the information theoretic measures, upon whichthe scoring function may be based, is as follows:

Uniformity:

The information theoretic measure of uniformity requires that theprobability of detecting a radioactive emission from each voxel, by oneof the views, be substantially equal, i.e., substantially uniform forall the voxels.

This is illustrated with reference to FIG. 9A. Basically, in one view, avoxel may have a high influence on the counts that are measured while,in another view, the same voxel may have a low influence on the countsthat are measured. For example, consider a voxel u(1;1;1), in relationto the views associated with the sectors S2 and S4. The voxel u(1;1;1)has a high influence on the counts that are measured by the viewassociated with the sector S4, but a low influence on the counts thatare measured by the view associated with the sector S2. The aim ofuniformity is to identify a set of views that will balance the influenceof each voxel for the entire set of views.

Separability:

The information theoretic measure of separability rates resolution, orthe ability to distinguish between a pair of close models of the bodystructure, each having substantially identical dimensions, so as todefine substantially identical volumes U having slightly differentdistributions of modeled organ targets.

For example, a pair of models of substantially identical volumes areillustrated in FIGS. 9B and 9C, wherein the respective modeled organtargets are HS, whose center is at a location (x;y;z)_(HS) and HS′,whose center is at a location (x;y;z)_(HS′). As noted above, thedisplacement along the x axis is delta1, which may be measured, forexample, in mm.

An optimal set of views, from the standpoint of separability, is thatwhich will best distinguish between HS of FIG. 9B and HS′ FIG. 9C. Thus,a score, in terms of separability, is given for the pair of models, thescore relating to a resolution as defined by the difference between thelocation of the two models. In the present example, the difference isdelta1, so the score given by the information theoretic measure ofseparability will relate specifically to a resolution as defined bydelta1 along the x-axis, relative to the locations of HS and HS′. Otherportions of the volume U and other displacements may have differentresolutions.

Additionally, as discussed above with regard to the model of FIG. 9D,volume U includes the modeled organ target HS″, whose center is at alocation (x;y;z)_(HS″). HS″ is displaced from HS of FIG. 9B, along thez-axis, the displacement denoted delta2, and is also displaced from HS′of FIG. 9C, along the x- and z-axes, the displacement denoted delta3.

Scores, in terms of separability, may be given to all the pairingcombinations, i.e., to the models of FIGS. 9B-9C, with regard to delta1;to the models of FIGS. 9B-9D, with regard to delta2; and to the modelsof FIGS. 9C-9D, with regard to delta3. An optimal set of views may beselected based on the average scores for all the pairing combinations;for example, the optimal set may be that whose average score for all thepairing combinations is the highest. Alternatively, a weighted averagemay be applied.

It will be appreciated that more than one modeled organ target may beincluded in the volume U. It will be further appreciated that a set ofviews may be selected so as to provide high resolution for portions ofthe volume U known to be susceptible to pathologies, and so as toprovide low resolution for portions of the volume U known to begenerally free of pathological features.

With regard to FIG. 9F, any pair of models of organs having differentdistributions of modeled organ targets, may be utilized for identifyingan optimal set of views in terms of separability.

Reliability:

The information theoretic measure of reliability rates repeatability inmeasurement, so that repeated reconstructions are not substantiallydifferent. Reliability may be scored with respect to a single model of abody structure, having a specific distribution of modeled organ targets,for example, any one of the models of FIGS. 9B-9E. Yet, preferably,several models of substantially identical volumes are provided, such as,for example, the four models of FIGS. 9B-9E. Substantially identicalsets of views may be applied to all the models and may be scored withrespect to reliability. The optimal set is selected based on its averagescore for the plurality of the models. For example, the optimal set maybe that whose average score for the plurality of the models is thehighest.

The four models of organs of FIG. 9F, each of which has a slightlydifferent distribution of modeled organ targets, may also be used foridentifying an optimal set of views in terms of reliability.

Weighted Combination:

A weighted combination of several information theoretic measures mayalso be used. For example, a plurality of models may be provided, allhaving substantially identical dimensions and volumes, as follows:

i. a first model of the volume U, free of modeled organ targets, as seenin FIG. 9A, for scoring sets of views in terms of uniformity;

ii. at least one pair of models of the volume U, with slightly differentdistributions of modeled organ targets, as seen in any pair of FIGS.9B-9C, 9B-9D, and (or) 9C-9D, for scoring sets of views in terms ofseparability;

iii. at least one model of the volume U, with a given distribution ofmodeled organ targets, as seen in any one of FIGS. 9B, 9C, 9D, and (or)9E, for scoring sets of views in terms of reliability.

Identical sets of views may be applied to all the models of the volumeU, and each view may be scored in terms of uniformity, separability, andreliability. An optimal set of views may be selected based on asummation of the three scores, or based on a weighted average of thethree scores.

The Greedy Construction

Some approaches for selecting an optimal set are based on determining arequired quality of reconstruction, and finding a set of views thatmeets that requirement. Others are based on fixing the size for the set(i.e., the number of views in the set) and maximize the quality of thereconstruction for the given set size. Still other approaches defineboth a desired size for the set and a desired quality of reconstructionand search for a set of the desired size, which meets the desiredquality of reconstruction.

However, given a desired size for a set of views and a desired qualityof reconstruction, while it may be possible to search through allpossible sets of the desired size, scoring each, in order to identifythe set that meets the desired quality, the task may be monumental. Forexample, where the collection of views includes several thousand views,and a set size of 100 is desired, rating each combination of 100 viewswould be computationally impractical.

An alternative approach is the Greedy Construction. When applying theGreedy Construction, an information theoretic measure is chosen, forexample, separability, and an initial set of a minimal number of viewsis defined. The set is gradually built up, so that with every addition,a view is picked so as to maximize the chosen information theoreticmeasure of the set.

This may be illustrated with reference to FIG. 9E. Given thatseparability is the chosen information theoretic measure, and an initialset of view S1 is defined, the additions of views S2 and S3 may then becompared in order to determine with which of them separability ismaximized. Intuitively, for the present example, the addition of S3 willmaximize the chosen information theoretic measure of the set.

It will be appreciated that other scoring functions, as known, maysimilarly be used.

Performing Measurements

The advantage of the method of the present invention, of predefining aset of views based on a model of a body structure, using an informationtheoretic measure, so as to optimize the functional information from theviews of the corresponding body structure, in vivo, becomes apparentwhen compared with the prior art alternatives. The prior art relies onobtaining random views, in vivo, or views dictated by anatomicalconstraints, with no rigorous approach to the manner by which they arechosen.

The method of the present invention, of predefining a set of views,based on a model of a body structure, using an information theoreticmeasure, so as to optimize the functional information from the views ofthe corresponding body structure, in vivo, is further illustratedhereinbelow, with reference to FIG. 10.

FIG. 10 illustrates, in flowchart form, a method 320 of functionalimaging, tailored for imaging a body structure optimized with respect tothe functional information gained about the body structure, by using thepredefined optimal set of views, in accordance with embodiments of thepresent invention. The method 320 comprises:

in a box 322: providing a model of a body structure, based on itsgeometry;

in a box 324: providing a model of anatomical constraints, which limitaccessibility to the body structure;

in a box 326: providing a collection of views of the modeled bodystructure, obtained within the modeled anatomical constraints;

in a box 328: providing a scoring function, by which any set of at leastone view, from a collection of views is scorable with a score that ratesinformation, obtained from the modeled body structure by the set;

in a box 330: forming sets of views from the collection of views andscoring them, with the scoring function;

in a box 332: selecting a set of views from the collection of views ofthe modeled body structure, based on its score, as the predefined set ofviews; and

in a box 334: performing radioactive-emission measurements of an in-vivobody structure that corresponds to the body structure that has beenmodeled, selectively at the predefined set of views.

It will be appreciated that the region-of-interest 200 may include anorgan, such as a heart or a pancreas, a gland, such as a thyroid glandor a lymph gland, blood vessels, for example, the coronary artery or thepulmonary artery, a portion of an organ, such as a left atrium of aheart, a bone, a ligament, a joint, a section of the body, such as achest or an abdomen, or a whole body.

A still more powerful approach may be achieved by taking the method ofthe present invention through second and third iterations, so as to zoomin on suspected pathological features that are identified. Specifically,when a suspected pathological feature is identified, a second, innerregion-of-interest, limited to the region of the pathological featureand its surrounding anatomical structure, can be identified and modeled.An optimal pathology set of views, specifically for the second, innerregion-of-interest, may be predefined, based on information theoreticmeasures, as before. This is illustrated hereinbelow, with reference toFIGS. 11 and 12.

Referring further to the drawings, FIG. 11 pictorially illustrates amethod 340 for zooming in on a suspected pathological feature, as aprocess of two or more iterations, in accordance with embodiments of thepresent invention, as follows:

In I: The region-of-interest 200, associated with the body structure215, is defined for the body section 230.

In II: The model 250 of the volume U is provided for theregion-of-interest 200, possibly with one or several of the modeledorgan targets HS, and within the anatomical constraints AC, forobtaining the optimal set of views for the region-of-interest 200. Theoptimal set of views is then applied to the body section 230.

In III: When a suspected organ target 213 is identified, in vivo, byradioactive-emission measurements at the optimal set of views, a second,inner region-of-interest 200′ is defined, including the suspectedpathological feature.

In IV: A model 250′ of a volume U′ is provided for the second, innerregion-of-interest 200′, preferably, with at least one modeled organtarget HS, simulating the suspected organ target 213, for obtaining anoptimal pathology set of views for the region-of-interest 200′. Thesecond, pathology set of views is then applied to the body section 230.

Referring further to the drawings, FIG. 12 illustrates, in flowchartform, the method 340, for zooming in on a suspected pathological featureof the body structure, as a process of two iterations, in accordancewith embodiments of the present invention. The method 340 comprises:

in a box 342: providing a model of a body structure, based on itsgeometry;

in a box 344: providing a model of anatomical constraints, which limitaccessibility to the body structure;

in a box 346: providing a first collection of views of the modeled bodystructure, obtained within the modeled anatomical constraints;

in a box 348: providing a first scoring function, by which any set of atleast one view, from a collection of views, is scorable with a scorethat rates information, obtained from the modeled body structure by theset;

in a box 350: forming sets of views from the first collection of views,and scoring them, with the first scoring function;

in a box 352: selecting a set of views from the first collection ofviews of the modeled body structure, based on its score, as thepredefined set of views;

in a box 354: performing radioactive-emission measurements. of anin-vivo body structure that corresponds to the body structure that hasbeen modeled, selectively at the predefined set of views;

in a box 356: identifying a suspected pathological feature, in thein-vivo body structure;

in a box 358: providing a model of the suspected pathological feature,based on its location in the body structure and general medicalknowledge;

in a box 360: providing a model of the anatomical constraints, whichlimit accessibility to the suspected pathological feature;

in a box 362: providing a second collection of views of the modeledsuspected pathological feature, obtained within the modeled pathology'sanatomical constraints;

in a box 364: providing a second scoring function;

in a box 365: forming sets of views from the second collection of views,and scoring them, with the second scoring function;

in a box 366: selecting a set of pathology views from the secondcollection of views, based on its score, as the predefined pathology setof views; and

in a box 368: performing radioactive-emission measurements of thesuspected pathological feature, selectively at the predefined pathologyset of views.

It will be appreciated that the model of the suspected pathologicalfeature may be provided responsive to a patient's complaint, aphysician's examination, or based on input from another imaging system,for example, x-rays, CT, MRI, ultrasound, and gamma scanning, forexample, with a hand-held gamma camera, rather then based on thefindings of the first set of measurements, of the step 356, hereinabove.

Design of the Radioactive-Emission Camera

While the embodiments described with reference to FIGS. 5A-12 relate topredefining a set of optimal views for a given radioactive-emissioncamera and a body structure, another side of the same coin relates to anoptimal design of the radioactive-emission camera and camera system forthe body structure, optimized with respect to functional informationgained.

Thus, the embodiments described hereinbelow, with reference to FIGS.13A-15 illustrate methods of designing cameras and camera systems,optimized with respect to information gained about a body structure.

Referring further to the drawings, FIGS. 13A-13E schematicallyillustrate possible designs of the radioactive-emission camera 10, andthe process of obtaining views for a given camera design, in accordancewith embodiments of the present invention.

FIGS. 13A-13C schematically illustrate the radioactive-emission camera10 as a radioactive-emission camera 226 arranged for measuring theradioactive-emission-density distribution of three bodies, U1, U2 andU3. The volume U1 of FIG. 13A has been modeled with no modeled organtargets, in order to score the radioactive-emission camera 226 in termsof uniformity. The volume U2 of FIG. 13B includes two modeled organtargets, HS1 and HS2, and may be used for scoring theradioactive-emission camera 226 in terms of reliability. The volume U3of FIG. 13C includes two modeled organ targets, HS1 and HS2′, so as toform a pair with the volume U2 of FIG. 13B, and the pair may be used forscoring the radioactive-emission camera 226 in terms of separability.Additionally, the volume U3 may be used to obtain a second score interms of reliability, and the two reliability scores may be averaged. Itwill be appreciated that additional bodies, of different radioactiveemission density distributions may be used, for obtaining additionalscores in terms of reliability, and for forming additional pairs, foradditional scores in terms of separability, wherein the scores in termsof each scoring function may be averaged. Additionally, the scores ofthe three functions may be combined, for example, as a sum, or as aweighted average. It will be appreciated that only one of the scoringfunctions, or only two of the scoring functions may be used.Additionally or alternatively, another scoring function or other scoringfunctions may be used.

According to the present example, the camera 226 has two detecting units222A and 222B whose collimators are arranged in parallel. The twodetecting units 222A and 222B are adapted for motion in the directionsof ±x, within the camera 226, as shown by arrows 224 and 228, so as toprovide coverage of a plane within the bodies U1 U2 and U3, in parallelsectors. Upon reaching the end of the travel in the +x direction, asshown by the arrow 224, the two detecting units 222A and 222B may berotated in the direction of ω, as shown by an arrow 217, and return inthe −x direction of the arrow 228. In this manner, complete coverage ofthe whole body is provided. A representative collection of views of thecamera 226 may be defined as a set of views of the bodies U1, U2, andU3, taken at predetermined increments of Δx and Δω.

Intuitively, a set formed of parallel sectors may score poorly in termsof uniformity since radioactive emissions from voxels closer to thedetecting unit have higher probabilities of being detected thanradioactive emissions from voxels far from the detecting unit.Additionally, a set formed of parallel sectors may score poorly in termsof separability, since it cannot distinguish between two models, whichonly differ in the depth of a pathological feature, along the z-axis.

FIG. 13D schematically illustrate the radioactive-emission camera 10 asa radioactive-emission camera 220, arranged for measuring theradioactive-emission-density distribution of the volume U2, which may beused for scoring the radioactive-emission camera 220 in terms ofreliability.

The camera 220 has the two detecting units 222A and 222B, arranged tosweep a plane within the volume U2, in a windshield-wiper-like manner,along ±θ, as illustrated by arrows 216 and 218. When sweeping along ±θis completed, the detecting units 222A and 222B rotate a few degreesalong ω, as illustrated by the arrow 217, and sweeping along ±θ isrepeated in the new orientation. In this manner, coverage of the wholevolume U2 is performed, from two locations and a large plurality oforientations. A representative collection of views of the camera 220 maybe defined as a set of views of the volume U2, taken at predeterminedincrements of Δθ and Δω.

The significance of the present embodiment, is as follows:

i. The different detecting units 222A and 222B provide views fromdifferent orientations; and

ii. The different detecting units 222A and 222B may change their vieworientations.

A score may be applied to this set, based on the information theoreticmeasure of reliability.

It will be appreciated that similarly, the camera 220 may be arrangedfor measuring the radioactive-emission-density distribution of thevolume U1 (FIG. 13A) and of the volume U3 (FIG. 13C), and possibly alsoof other bodies, in order to score the radioactive-emission camera 220also in terms of uniformity and separability. The scores of the threefunctions may be combined, for example, as a sum, or as a weightedaverage. It will be appreciated that only one of the scoring functions,or only two of the scoring functions may be used. Additionally oralternatively, another scoring function or other scoring functions maybe used.

Intuitively, the set of representative collection of views of thepresent example is likely to score more highly in terms of separabilitythan that of the camera 226 of FIG. 13A, as it provides views fromdifferent locations and orientations.

In FIG. 13E the detecting units 222A and 222B of the camera 220 arefurther adapted for motion in the directions of ±x, within the camera220, as shown by the arrows 224 and 228.

Intuitively, the set of representative collection of views of thepresent example is likely to score more highly in terms of all threeinformation theoretic measures, than those of the camera of FIGS.13A-13C and of the camera of FIG. 13D, as the present example providesviews from a large plurality of locations and orientations.

In this manner, the information theoretic measures may be used forscoring representative collections of views of suggested camera designs,and an optimal camera design may be chosen based on this score, asdescribed hereinbelow, with reference to FIG. 14, hereinbelow.

FIG. 14 illustrates, in flowchart form, a method 370 for identifying acamera optimized with respect to information gained about the bodystructure. The method 370 comprises:

in a box 372: providing a model of a body structure, based on itsgeometry;

in a box 374: providing a model of anatomical constraints, which limitaccessibility to the body structure;

in a box 375: providing representative collections of views of themodeled body structure, within the modeled anatomical constraints, fordifferent camera designs;

in a box 376: providing a scoring function, by which each representativecollection of views, associated with a specific camera design, isscorable with a score that rates information, obtained from the bodystructure;

in a box 377: scoring the representative collections of views, with thescoring function; and

in a box 378: selecting a camera design, based on the score of itsrepresentative collection of views.

In this manner, a comparison of the quality of the data that may beproduced by each camera design can be made. This analysis is importantat the camera-design stage, in order to eliminate situations where viewswhich are anatomically possible and which are desired from thestandpoint of information theoretic measures, are unattainable becauseof camera design limitations. For example, the camera 190 of FIG. 4C,hereinabove, cannot be used for the windshield-wiper-like motion, shownin FIG. 13D, by the arrows 216 and 218; however, this type of coveragehas proved very valuable. The method 370 may, however, be suitable foranother camera design.

Additionally, when selecting a camera design, it is generally desired toconsider secondary issues, such as the rate of data collection, the costof the camera, the complexity of the design, for example, in terms ofthe number of motors, motion-transfer systems, and the like.

The rate of data collection is important both because it may beassociated with patient discomfort and because it affects the number ofpatients that may be examined in a period of time. Where data collectionwith one camera design may take an hour and with another camera designmay take 10 minutes, the design of the faster camera is highlyadvantageous. Complexity and cost are important because they affect theaccessibility of the camera to the general public.

Thus, a design scoring function may be provided, for rating each cameradesign with a design score, based on any one or a combination of thesecondary issues. The design scoring function may be used for selectinga camera design from several that have been found acceptable in terms ofthe quality of the data, by the method 370 of FIG. 14.

Referring further to the drawings, FIG. 15 illustrates, in flowchartform, a method 380 of selecting a camera design, optimized with respectto information gained about a body structure and secondary issues, inaccordance with embodiments of the present invention. The method 380comprises:

in a box 382: providing a model of a body structure, based on itsgeometry;

in a box 384: providing a model of anatomical constraints, which limitaccessibility to the body structure;

in a box 385: providing representative collections of views of themodeled body structure, within the modeled anatomical constraints, fordifferent camera designs;

in a box 386: providing a scoring function, by which each representativecollection of views, associated with a specific camera design, isscorable with a score that rates information, obtained from the bodystructure;

in a box 387: scoring the representative collections of views, with thescoring function;

in a box 388: identifying several camera designs as acceptable, based onthe scores of their representative collections of view;

in a box 390: providing a design scoring function, by which each cameradesign is scorable, based on the secondary issues;

in a box 392: scoring the acceptable camera designs with a design score;

in a box 394: selecting a camera design, based on its design score.

It will be appreciated other manners of combining the scoring function,which rates information, and the design scoring function, which ratessecondary issues, are possible. For example, a combined scoringfunction, which takes all these factors into account, may be used.

As will be shown, hereinbelow, with reference to FIGS. 18A-22X, manydifferent camera designs may provide substantially the same information,but are different in terms of their secondary considerations, that is,at different rates of data collection, different costs and differentcomplexity of their designs, for example, in terms of the number ofmotors and motion-transfer systems. Thus these may score similarly interms of functional information, and a design scoring function may beused to choose from amongst them.

Referring further to the drawings, FIGS. 16A-16L schematicallyillustrate viewing the elliptical model 250 of the volume U, with thecamera 10, as illustrated specifically in FIGS. 20A-20H, hereinbelow.

FIGS. 16A-16K show the spanning of the elliptical model 250 of thevolume U, along an x-z plane, by the sweeping views. FIG. 16L is apictorial representation of the camera 10 of FIGS. 20A-20H and theelliptical model 250 of the volume U, in accordance with embodiments ofthe present invention.

The views, obtained in FIGS. 16A-16K may be used both for:

i. a collection of views for the volume U, from which an optimal set ofviews may be chosen, specific to a body structure, in accordance withthe teachings of FIGS. 8, 10, and 12, hereinabove, and

ii. a representative collection of views of the camera 10, foroptimizing a camera design, in accordance with the teachings of FIGS. 14and 15, hereinabove.

Imaging Schemes—Stop-Go, Interlacing and Continuous Acquisition

According to embodiments of the present invention there may be severalimaging schemes connected with the motion of the detecting units, blocksand/or assemblies as follows:

In a first embodiment the detecting units, blocks and/or assemblies aremoved to a position and collect photon emission data while stationary(herein referred to as the Stop-Go imaging scheme).

In a second embodiment, a version of the Stop-Go imaging scheme, amotion of each detecting unit or block or assembly is at a predeterminedangle per move (after each move data is collected while the detectingunit or block or assembly is stationary) and characterized by half theangle phase shift when scanning in opposite directions, so as to scanthe scanned region every half angle (herein referred to as theInterlacing imaging scheme).

In a third embodiment a motion of each detecting unit or block orassembly is without pause between minimum and maximum sweeping angles(herein referred to as the Sweeping Imaging Scheme).

Prescanning

Oftentimes it is desirable to perform a fast prescan of a subjectundergoing diagnosis, find a region-of-interest, thereafter collecthigher quality data from the region-of-interest. A prescan according toembodiments of the present invention can be performed by any imagingdevice, including, but not limited to, ultrasound and MRI or by aphysical inspection of the subject undergoing diagnosis. Alternatively,a prescan can be performed by the camera of the present inventionpreferably using the interlacing imaging scheme as is further describedabove or by broad view selection as is further described below.

EXAMPLES OF CAMERA SYSTEMS

Reference is now made to the following examples of radioactive-emissioncameras and camera systems, for a comparative study taught withreference to FIGS. 14 and 15.

Example 1

Referring further to the drawings, FIGS. 18A and 18B schematicallyillustrate the radioactive-emission camera 10, of the single detectingunit 12 (see FIGS. 1A and 17A). The single detecting unit 12 has amotion with respect to the overall structure 20, which is a combinationof a rotational motion around the x-axis, in the direction of ω, denotedby an arrow 44, and a translational motion along the x-axis, denoted byan arrow 46.

As a consequence, a spiral trace 48 is formed, for example, on an innersurface of a body lumen 232, as seen in FIG. 18B.

Preferably, the motions of the detecting unit 12 are contained withinthe overall structure 20, so that the external surface of the camera 10remains stationary. The external surface of the camera may be formed ofa carbon fiber, a plastic, or another material, which is substantiallytransparent to nuclear radiation.

Example 2

Referring further to the drawings, FIGS. 18C and 18D schematicallyillustrate the radioactive-emission camera 10, of the single block 90(FIGS. 1B and 17E). Note that all the detecting units 12 of the singleblock 90 move as a single body. The single block 90 has a motion withrespect to the overall structure 20, which is a combination of therotational motion around the x-axis, in the direction of ω, denoted bythe arrow 44, and the translational motion along the x-axis, denoted bythe arrow 46.

As a consequence, a plurality of spiral traces 49 is formed, forexample, on an inner surface of a body lumen, as seen in FIG. 18D.

Preferably, the motions of the block 90 are contained within the overallstructure 20, so that the external surface of the camera 10 remainsstationary, wherein the external surface of the camera is substantiallytransparent to nuclear radiation.

Example 3

Referring further to the drawings, FIGS. 19A-19E schematicallyillustrate the radioactive-emission camera 10, of the single block 90 ofa plurality of the detecting units 12.

For understanding the motion of the camera 10 of the present example, itis desirable to define a cylindrical coordinate system of a longitudinalaxis, x, and a radius r, wherein the motion around the longitudinalaxis, x, is denoted by ω, while the motion around the radius r isdenoted by φ.

The single block 90 has a motion with respect to the overall structure20, which is performed in steps, as follows:

i. the windshield-wiper like oscillatory motion, around the radius r, inthe direction of ±φ, as denoted by the arrow 50;

ii. the translational motion along the x-axis, by an amount Δx, to a newmeasuring position, as denoted by the arrow 46;

iii. after traversing the length of the camera, a rotational motionaround the x-axis, in the direction of ω, by an amount Δω, as denoted bythe arrow 44, in order to perform the same measurements at a newmeasuring position of ω.

As a consequence, a plurality of broken line traces 59 is formed, asseen in FIG. 19E.

Preferably, the motions of the block 90 are contained within the overallstructure 20, so that the external surface of the camera 10 remainsstationary, wherein the external surface of the camera is substantiallytransparent to nuclear radiation.

Example 4

Referring further to the drawings, FIGS. 20A-20H schematicallyillustrate the radioactive-emission camera 10, having at least one pair,or a plurality of pairs of blocks 90, adapted for the windshield-wiperlike oscillatory motion, around the radius r, as denoted by the arrows50. The oscillatory motions may be synchronized in an antipodal manner,so as to be diametrically opposed to each other, as shown in FIGS. 20Band 20E, by the arrows 54, and as shown in FIGS. 20C and 21F by thearrows 56. It will be appreciated that the oscillatory motions need notbe synchronized in an antipodal manner. Rather, all the blocks 90 maymove in synchronized motion, or each block 90 may move independently. Itwill be appreciated that an odd number of blocks 90 is also possible.

Additionally, a rotational motion of the overall structure 20, aroundthe x-axis in the direction of ω, an amount Δω, to a new measuringposition along ω, is provided, after each step of the oscillatorymotion, as shown in FIG. 20D, by an arrow 52.

The resultant traces are the plurality of broken line traces 59, as seenin FIG. 20G.

In essence, the camera 10 of FIGS. 20A-20F and 20H provides views whichare essentially the same as those of FIGS. 19A-19E, but in a moreefficient way, since a plurality of blocks is involved.

In accordance with the present example,

i. The different blocks 90 provide views from different orientations;and

ii. The different blocks 90 may change their view orientations.

Preferably, the motions of the blocks 90 are contained within theoverall structure 20, so that the external surface of the camera 10remains stationary, wherein the external surface of the camera issubstantially transparent to nuclear radiation.

In particular, as seen in FIG. 20H, an internal structure 21 may containall the blocks 90, configured to move together, as a rigid structure,while the overall structure 20 and the external surface of the camera 10remain stationary.

The operational manner of the camera 10 of FIGS. 20A-20H is describedwith reference to FIG. 23C, hereinbelow.

It will be appreciated that the single detecting units 12 may be used inplace of the single blocks 90.

Example 5

Referring further to the drawings, FIGS. 21A-21D schematicallyillustrate the radioactive-emission camera 10, having at least one pair,or a plurality of pairs of blocks 90, adapted for the windshield-wiperlike oscillatory motion, around the radius r, as denoted by the arrow50. The oscillatory motions are preferably synchronized in an antipodalmanner, so as to be diametrically opposed to each other, as in, forexample, FIG. 20B. It will be appreciated that the oscillatory motionsneed not be synchronized in an antipodal manner. Rather, all the blocks90 may move in synchronized motion, or each block 90 may moveindependently. It will be appreciated that an odd number of blocks 90 isalso possible.

Additionally, a rotational motion of each of the blocks 90 around thex-axis, in the direction of ω, an amount Δω, to a new measuring positionalong ω, is provided, after each step of the oscillatory motion, asshown in FIG. 21B, by the arrows 44. This is unlike FIG. 20D, whereinthe internal structure 21 moved as a rigid unit, as shown in FIGS. 20Dand 20H.

The resultant traces are the plurality of broken line traces 59, as seenin FIG. 21D. In essence, the camera 10 of FIGS. 21A-21C provides viewswhich are essentially the same as those of FIG. 19E, and of FIG. 20G,but in a different manner.

In accordance with the present example,

i. The different blocks 90 provide views from different orientations;and

ii. The different blocks 90 may change their view orientations.

Preferably, the motions of the blocks 90 are contained within theoverall structure 20, so that the external surface of the camera 10remains stationary, wherein the external surface of the camera issubstantially transparent to nuclear radiation.

It will be appreciated that the detecting units 12 may be used in placeof the blocks 90.

Example 6

Referring further to the drawings, FIGS. 22A-22C and 22E-22Gschematically illustrate the radioactive-emission camera 95, comprisingthe plurality of assemblies 92, each assembly 92 being similar inconstruction to the structure 21 of FIG. 20H, in accordance withembodiments of the present invention.

The plurality of assemblies 92 are preferably arranged in parallel, andtheir rotational motions, around the x-axis, may be synchronized in anantipodal manner, so as to be diametrically opposed to each other, asshown in FIG. 22C, by arrows 62, and in FIG. 22G, by arrows 64. It willbe appreciated that the rotational motion around the x-axis need not besynchronized in an antipodal manner, and may be performed in parallel,or independently.

Thus, the resultant traces are a large plurality of the broken linetraces 66 and 68, as seen in FIGS. 22D and 22H.

In essence, the camera 95 provides views which are essentially the sameas those of FIGS. 19E, 20G, and 21D, but far more efficiently, since aplurality of assemblies is involved.

In accordance with the present example,

i. The different blocks 90 provide views from different orientations;

ii. The different blocks 90 may change their view orientations;

iii. The different assemblies 92 provide views from differentorientations; and

iv. The different assemblies 92 may change their view orientations.

The operational manner of the camera 95 is described with reference toFIG. 23D, hereinbelow, for the at least two assemblies 92A and 92B.

Preferably, the motions of the blocks 90 and of the assemblies 92 arecontained within the overall structure 20, so that the external surfaceof the camera 95 remains stationary, wherein the external surface of thecamera 95 is substantially transparent to nuclear radiation.

It will be appreciated that camera 95 may include a plurality ofassemblies 92, which are not parallel to each other. For example, theassemblies 92 may be at right angles to each other, or at some otherangle.

It will be appreciated that the assemblies 92 may include the detectingunits 12 rather then the blocks 90.

Referring further to the drawings, FIGS. 22I-22X schematicallyillustrate possible individual motions for blocks 90, in accordance withembodiments of the present invention.

In essence, in the present example, the blocks 90 are not arranged inassemblies 92, and each moves independently of the other blocks 90.

In accordance with a first embodiment, of FIGS. 22I-22M, each of theblocks 90 may be in communication with two motion providers, forproviding the oscillatory motion about the r-axis, as seen by the arrows50, and for providing the rotational motion around the x-axis, as seenby the arrows 44.

A first set of measurements is performed as the blocks 90 oscillateabout the r-axis, as seen in FIG. 22J.

The blocks 90 then rotate around the x-axis, to a new measuringposition, as seen in FIG. 22K.

A second set of measurements is performed at the new position, as theblocks 90 oscillate about the r-axis, as seen in FIG. 22M.

The blocks then rotate around the x-axis, to a new measuring position,as shown in FIG. 22K, and so on.

The resultant traces are a large plurality of the broken line traces 66and 68, as seen in FIGS. 22J and 22M, and are substantially the same asthose of FIGS. 22D and 22H.

In accordance with a second embodiment, each of the blocks 90 (FIG. 22N)may be in communication with two motion providers, for providing anoscillatory motion about the x-axis as seen by an arrow 61, and arotational motion around the x-axis, as seen by an arrows 63. Theresultant trace is star shaped, as seen by the lines 65 of FIG. 22O.

Additionally, a tertiary motion provider may be included, for providinga cluster 67 of overlapping lines, for a substantially complete coverageof a region, for example, as seen in FIG. 22P by a cluster 67 of theoverlapping star-shaped lines 65.

It will be appreciated that many other forms of motion may be provided,and may include one, two, three or more motion providers.

FIGS. 22Q and 22R illustrate another set of dual motions andcorresponding measurements for an individual one of the blocks 90, whileFIGS. 22S and 22T illustrate those of a set of a tertiary motion, bythree motion providers.

Similarly, FIGS. 22U and 22V illustrate still another set of tworotational motions and corresponding measurements, provided for eachblock individually, and FIGS. 22W and 22X illustrate still another setof a rotational motion, provided for each block individually, andcoupled with a linear motion.

It will be appreciated that each block 90, or detecting unit 12 may beprovided with at least one, and preferably, two, three, or possibly asmany as six degrees of motion, for example, rotational motion around thex, y, and z, axis, or oscillatory motion about these axes, and possiblyalso translational motion, along the x, and (or) y, and (or) the z-axis.In this manner, each block 90 may be preprogrammed to view each portionof the body section 230, in accordance with some predetermined schedule,dedicated to the specific block 90. For example, one of the blocks 90may perform oscillatory motion, while an adjacent one of the blocks 90may perform rotational motion.

Referring further to the drawings, FIGS. 22Y and 22AA schematicallyillustrate a center of viewing 200A, for a given camera design, inaccordance with embodiments of the present invention.

As the detecting units 12, or blocks 90, or assemblies 92 move or sweepacross the region-of-interest volume U, for example, as illustrated bythe arrows 203, different portions of the volume U are viewed atdifferent frequencies and duration. The region which is viewed mostheavily may be defined as the center of viewing 200A. It is surroundedby regions, which are viewed somewhat less. In essence, a shell-likeviewing structure may be formed, with decreasing viewing intensities, asthe distance from the center of viewing 200A increases. This isillustrated, for example, by the center of viewing 200A and surroundingshells 201, 209, and 211.

It will be appreciated that the center of viewing 200A may be a regionof uniform viewing, rather than a mere point. For example, the region201 may be a region of uniform viewing, which forms the center ofviewing 200A.

Example 7

Having designed a radioactive-emission camera capable of obtaining acollection of views, and having predefined a set of views, which isoptimal for a body structure, based on its model, the task of performingmeasurements, selectively at the predefined set of views, would be quiteimpossible if it were to be performed manually. Generally, betweenseveral hundred and several thousand views are taken, and manuallytuning each to a predetermined location, orientation, and possibly alsoduration would be impractical. Therefore, the camera and method of thepresent invention are operative with an overall system, in whichcomputer controlled motion providers govern the motions of the detectingunits or of the overall camera. The computer may be any one of apersonal computer, a laptop, a palmtop, or another computer, adapted forcommunication with the camera, or a microcomputer, built into thecamera. Additionally, a combination of a microcomputer, built into thecamera, and an external computer such as a personal computer, a laptop,a palmtop, or the like, may be used.

Preferably, before measurements are performed, personal details are fedinto the computer, and the models of the body structure and anatomicalconstraints are adapted to these details. The personal details mayinclude age, sex, weight, body type, and the like.

Referring further to the drawings, FIGS. 23A-23D schematicallyillustrate a radioactive-emission camera system 400 in accordance withembodiments of the present invention.

As seen in FIG. 23A, the camera system 400 includes the camera 10,having a controller 404, in communication with one or several motionproviders 76, for sending signals of the locations and orientations ofviews to the one or several motion providers 76. The one or severalmotion providers 76, in turn, govern the motions of one or several ofthe detecting units 12. The one or several of the detecting units 12collect the measurements at the predefined locations and orientationsand communicate the data to the controller 404. Signals of new locationsand orientations are then communicated by the controller 404 to the oneor several motion providers 76. Each of the motion providers 76 maycontrol the motion of one of the detecting units 12 or of a plurality ofthe detecting units 12.

Preferably, the controller 404 registers the location and orientation ofeach of the detecting unit 12 as it moves. Additionally oralternatively, a position-tracking device may be associated with each ofthe detecting units 12.

Preferably, a position-tracking device 418 is associated with the camera10 as a whole, for registering its position with respect to, forexample, the body structure 215 (FIG. 5A).

A power supply 410 powers the camera 10. Alternatively, power may besupplied from the grid.

Preferably, a transceiver or transmitter 402, reports the measurementsto an external computer (not shown). Alternatively, a cable (not shown)may be used. Alternatively, the controller 404 includes a microcomputer,or the like, and performs the data analysis.

Additionally, the transceiver 402 may be adapted to receive input datarelating to the personal details of the patient, such as the age, sex,weight, body type, and the like, in order to adjust the model of thebody structure, hence the locations and orientations of the predefined,optimal set of views, to the particular patient.

Furthermore, the transceiver 402 may be adapted to receive input datafrom an ultrasound imager, for providing information such as location,size of the body structure and the like, by ultrasound imaging, in orderto adjust the model of the body structure, hence the locations andorientations of the predefined, optimal set of views, to the particularpatient.

Preferably, the motion of the one or several motion providers 76 relatesto motion of the detecting units 12, with respect to the camera overallstructure 20 (FIG. 20H), for example, by the motion of detecting units222A and 222B (FIG. 13E), with respect to the overall structure 220, asshown by the arrows 216 and 218.

Alternatively or additionally, the motion of the one or several motionproviders 76 may relate to motion of the overall structure 20 or 220 asa whole, for example, as taught with reference to FIG. 13E, by themotion the camera 220, as shown by the arrows 224 and 228.

It will be appreciated that the controller 404, while being part of thesystem 400, need not part of the actual camera 10. Rather it may be anexternal computer, communicating with the camera 10 either by cables orvia a transceiver.

As seen in FIG. 23B, the camera 10 includes the blocks 90, eachcomprising a plurality of the detecting units 12, each block 90 movingas a single body.

As seen in FIG. 23C, the individual motion of the blocks 90 is governedby a secondary motion provider 78. Additionally, all of the blocks 90form an assembly 92, which moves by the motion provider 76, for example,within an internal structure 21, as illustrated hereinbelow withreference to FIG. 20H. For example, the secondary motion provider 78 mayprovide the motion described by the arrows 50 of FIGS. 20B and 20C or20F and 20F, hereinbelow while the motion provider 76 may provide themotion described by the arrow 52 of FIG. 20H, hereinabove.

It will be appreciated that the multiple motions may be provided to thedetecting units 12, rather then to the blocks 90.

It will be appreciated that a tertiary motion provider may also be usedand that many arrangements for providing the motions are possible, andknown.

As seen in FIG. 23D, at least two assemblies 92 may be provided, eachwith a dedicated motion provider 76 and a dedicated secondary motionprovider 78. It will be appreciated that the multiple motions may beprovided to the detecting units 12, rather then to the blocks 90. Itwill be appreciated that tertiary motion providers may also be used andthat many arrangements for providing the motions are possible, andknown.

In the example of FIG. 23D, the controller 404, while being part of thesystem 400, may not be part of the actual camera 10. For example, it maybe an external computer, communicating with the camera 10 either bycables or via a transceiver.

EXAMPLES OF CAMERA SYSTEMS FOR SPECIFIC APPLICATIONS

Reference is now made to the following examples of radioactive-emissioncameras and camera systems, for specific applications.

Example 8

Referring further to the drawings, FIGS. 24A-32 schematically illustratethe radioactive-emission camera 10, for the prostate, in accordance withan embodiment of the present invention.

FIGS. 24A-24C schematically illustrate the modeling of a prostate and alocation of pathology, as a process of two iterations, for zooming in onthe pathology, in accordance with embodiments of the present invention.

FIG. 24A schematically illustrates a body section 230, which includes aprostate 260, which has sections 262, 264 and 266, and a pathology 265in section 264. Additionally, the body section 230 includes a rectum268, from which the prostate 260 may be viewed.

FIG. 24B schematically illustrates the model 200 of the body section230, including the prostate 260, of sections 262, 264 and 266, and therectum 268. An optimal set of views is predefined based on the model 200and a first scoring function. The first scoring function may be based onregions of interest similar to the pathology 265, as known, from medicalrecords of common pathologies. Measurements of radioactive emission arethen taken at the predefined views, in vivo, for the prostate 260.

As seen in FIG. 24C, upon discovering the pathology 265, by the in-vivomeasurements, a second model 250 of the section 264 is made, for zoomingin on the pathology 265, and a second optimal set of views ispredefined, based on the second model 250 of the section 264 and asecond scoring function, for zooming in on the pathology 265.Measurements of radioactive emission are then taken at the predefinedsecond set of views, in vivo, for the section 264 and the pathology 265.

It will be appreciated that the first and second scoring functions maybe based on any one of or a combination of the information theoreticmeasures of uniformity, separability, and reliability. It will befurther appreciated that the first and second scoring functions need notbe the same.

FIGS. 25A-25E illustrate an external appearance and an internalstructure, of the camera 10. The radioactive-emission camera 10 for theprostate has an extracorporeal portion 80 and an intracorporeal portion82, which is adapted for insertion into a rectum. The overall structure20 of the intracorporeal portion 82 is preferably shaped generally as acylinder and defines a longitudinal axis along the x-axis, and a radius,perpendicular to the longitudinal axis. The intracorporeal portion 82preferably includes two pairs of assemblies 90, arranged in the overallstructure 20. It will be appreciated that another number of assemblies,for example, a single pair, or three pairs, is similarly possible. Anodd number of assemblies is similarly possible. In essence, the camera10 of the present example is analogous to the camera 10 of FIG. 23C andFIGS. 20A-20F and 20H, and particularly, to FIG. 20H. The rotationalmotion, in the direction of the arrow 52 of FIG. 20H, is provided by amotor 88 (FIG. 25C) and a main shaft 85. The motor 88 may be an electricmotor, for example, a servo motor. The motor 88 and main shaft 85,together, form a motion provider 76 for the rotational motion in thedirection of the arrow 52 of FIG. 20H. The oscillatory motion, in thedirection of the arrows 50 of FIG. 20B, is provided by a secondary motor86, a secondary shaft 84 and a motion transfer link 74. The secondarymotor 86 may also be an electric motor, for example, a servo motor. Thesecondary motor 86, secondary shaft 84 and the motion transfer link 74,together, form the secondary motion provider 78, in the direction of thearrows 224 and 228 of FIG. 13E.

The significance of the present embodiment, is as follows:

i. The different assemblies 90 provide views from differentorientations; and

ii. The different assemblies 90 may change their view orientationsindependent of each other.

It is important to point out that during the operation of the camera 10,the external surface of the intracorporeal portion 82 (FIG. 25A) remainsstationary, while the internal structure 21 (FIG. 25C) rotates aroundthe x-axis. The external surface of the intracorporeal portion 82 may beformed of a carbon fiber, a plastic, or another material, which issubstantially transparent to nuclear radiation.

FIG. 25E illustrates further the internal structure of theradioactive-emission camera for the prostate, in accordance with anembodiment of the present invention, showing the assemblies 90 withinthe overall structure 20. Each assembly may be a single detecting unit12, or a plurality of the detecting units 12, for example, 36 of thedetecting units 12, for example, as an array of 6×6, or 99 of thedetecting units 12, for example, as an array of 11×9, or another numberof the detecting units 12, arranged as an array or arranged in anothergeometry.

Referring further to the drawings, FIG. 26 illustrates further theinternal structure of the radioactive-emission camera for the prostate,in accordance with an embodiment of the present invention, showing theoscillatory motion (in the direction of the arrows 50 of FIGS. 20A, and20C) of the assemblies 90 within the overall structure 20.

FIGS. 27-28 schematically illustrate the radioactive-emission camera 10,for the prostate, in accordance with another embodiment of the presentinvention. In accordance with the present embodiment, the camera 10further includes an ultrasound transducer 85, arranged, for example, atthe tip of the intracorporeal portion 82.

FIG. 27 illustrates the external appearance of the camera 10 with theultrasound transducer 85 at its tip.

FIG. 28 illustrates the ultrasound wave 87, impinging on the prostate260.

FIGS. 29A-29C illustrate the co-registering of a radioactive-emissionimage and an ultrasound image, to illustrate the functional informationof the radioactive-emission image with the structural information of theultrasound image. The ultrasound image is seen in FIG. 29A, theradioactive-emission image is seen in FIG. 29B, and the co-registeringof the two is seen in FIG. 29C.

FIG. 30 schematically illustrates the radioactive-emission camera 10,for the prostate, in accordance with another embodiment of the presentinvention. In accordance with the present embodiment, the camera 10further includes an ultrasound transducer 85, and a surgical needle 83,in a needle guide 81, arranged alongside the camera 10, for obtaining abiopsy or for other minimally invasive procedures. FIG. 30 schematicallyillustrates the surgical needle 83 as it penetrates the prostate 260from the rectum 268.

FIGS. 31 and 32 schematically illustrate the manner of guiding theneedle 83. A track 89 shows the surgeon the direction of the needle,while the camera 10 produces the functional image of the pathology 265in the prostate 260. By moving the camera 10, manually, the surgeon canalign the track 89 with the pathology 265, as shown in FIG. 32. Oncealigned, he can insert the needle 83, as shown in FIG. 30.

Example 9

Referring further to the drawings, FIG. 33 pictorially illustrates themethod 340 for zooming in on a suspected pathological feature in awoman's reproductive system, as a process of two or more iterations, inaccordance with embodiments of the present invention, as follows:

As seen in FIG. 33, the method 340 may be described, pictorially, asfollows:

In I: The region-of-interest 200, associated with a woman's reproductivesystem 270, is defined for the body section 230 having the bodystructure 215.

In II: The model 250 of the volume U, is provided for theregion-of-interest 200, possibly with one or several of the modeledorgan targets HS, and within the anatomical constraints AC, forobtaining the optimal set of views for the region-of-interest 200. Theoptimal set of views is then applied to the body section 230.

In III: When a suspected organ target 213 is identified, in vivo, byradioactive-emission measurements at the optimal set of views, a second,inner region-of-interest 200′ is defined, encircling the suspectedpathological feature.

In IV: A model 250′ of a volume U′ is provided for the second, innerregion-of-interest 200′, preferably, with at least one modeled organtarget HS, simulating the suspected organ target 213, for obtaining anoptimal pathology set of views for the region-of-interest 200′. Thesecond, pathology set of views is then applied to the body section 230.

Referring further to the drawings, FIGS. 34A-34R schematicallyillustrate radioactive-emission measuring cameras 600, tailored forimaging the woman's reproductive system 270 and optimized with respectto the functional information gained, regarding the body structures ofthe woman's reproductive system, such as the cervix 274, the uterus 276,the ovaries 278, and the fallopian tubes 280 (FIG. 33), in accordancewith preferred embodiments of the present invention.

FIG. 34A schematically illustrates the basic radioactive-emissionmeasuring camera 600, for a body lumen, for example, the vagina 272, thecervix 274, the uterus 276, the rectum (not shown), or the sigmoid colon(not shown). The camera 600 includes an extracorporeal portion 610,which preferably comprises a control unit, and an intracorporeal portion630, having proximal and distal ends 631 and 633, with respect to anoperator (not shown).

The control unit of the extracorporeal portion 610 may include controlbuttons 612 and possibly a display screen 614, and may provideconnections with a computer station. It may receive power from a grid orbe battery operated. The control unit of the extracorporeal portion 610may further include a computer or a microcomputer. It will beappreciated that the control unit may be incorporated with theintracorporeal section 630, and operated remotely.

The intracorporeal portion 630 defines a cylindrical coordinate systemof x;r, wherein x is the longitudinal axis. The plurality of blocks 90along the length of the intracorporeal portion 630 is housed in aninternal structure 21 (FIG. 20H).

Each of the blocks 90 is adapted for the windshield-wiper likeoscillatory motion, around the radius r, as denoted by the arrows 50.The oscillatory motions may be synchronized in an antipodal manner, soas to be diametrically opposed to each other, as shown hereinabove inFIGS. 20B and 20E, by the arrows 54, and as shown hereinabove in FIGS.20C and 20F by the arrows 56. However, other motions are also possible.For example, the blocks 90 may move together, or independently. It willbe appreciated that an odd number of blocks 90 is also possible.

Additionally, the internal structure 21 is adapted for rotational motionaround the x-axis, in the direction of ω, wherein after each step ofoscillatory motion at a certain orientation of ω, the internal structurerotates by a step to a new orientation of ω, and the oscillatory motionis repeated.

As a consequence, a plurality of broken line traces 59 are formed, inthe body section 230, as seen in FIG. 34J.

Preferably, the controller or the computer registers the locations andorientations of each detecting unit or block and correlates themeasurements with the corresponding positions and orientations.

A position-tracking device 635 may also be used, for providinginformation regarding the position of the camera 600 relative to a knownreference. For example, if a structural scan, or another scan by anotherimager has been made, the position-tracking device 635 may be used toregister that scan with the measurements of the camera 600.

It will be appreciated that the camera 600 may include detecting units12 rather then blocks 90.

Preferably, the overall structure 20 remains stationary and issubstantially transparent to nuclear radiation, formed, for example, ofa hydrocarbon material.

The intracorporeal portion 630 may further include dedicated electronics634 and motion providers 636, such as miniature motors and motiontransfer systems, as known.

FIGS. 34B and 34C schematically illustrate side and distal views,respectively, of the radioactive-emission measuring camera 600, havingan ultrasound imager 640 at its distal tip 633. The ultrasound imager640 may provide a structural image which may be correlated with thefunctional image. Additionally, it may be used for providing the sizeand location of the body structure for modeling. Furthermore, it may beused for providing attenuation correction to the radioactive emissionmeasurements.

FIGS. 34D and 34E schematically illustrate side and distal views,respectively, of the radioactive-emission measuring camera 600, havingan MRI imager 642 at its distal tip 633. The MRI imager 642 may providea structural image which may be correlated with the functional image.Additionally, it may be used for providing the size and location of thebody structure for modeling. Furthermore, it may be used for providingattenuation correction to the radioactive emission measurements.

FIGS. 34F-34I schematically illustrate the radioactive-emissionmeasuring camera 600, having a distal block 90A at its distal tip 633.The distal block 90A at the distal tip is also adapted for oscillatorymotion, but about the x-axis, as seen by an arrow 53. When combined withthe rotational motion around the x-axis, it produces traces 55 in theshape of a star, in the body section 230, as seen in FIG. 34K.

It will be appreciated that a single distal detecting unit may beemployed in place of the distal block 90A.

FIGS. 34L-34Q schematically illustrates the radioactive-emissionmeasuring camera 600, for a body lumen, having the distal block 90A atits distal tip 633, adapted for a deployed and a retracted position, andfor oscillatory motion about the x-axis, when deployed. The camera 600further has the ultrasound imager 640 at its distal tip 633, as a ring,similarly having a deployed and a retracted position.

FIGS. 34N-34P illustrate the distal block 90A deployed, and theultrasound imager 640 retracted. In this manner, the ultrasound imager640 does not obstruct the oscillatory motion of the distal block 90A atthe distal tip 633.

FIG. 34Q illustrates the distal block 90A retracted and the ultrasoundimager deployed so the distal block 90A does not obstruct the view ofthe ultrasound imager. It will be appreciated that the ultrasound imageis to be taken once, from the distal tip 633, while theradioactive-emission measurements are to be taken at a plurality oforientations, from the distal tip 633.

FIG. 34R illustrates the camera 600 with a cable 620 connecting theintracorporeal portion 630 and the extracorporeal portion 610, forexample, for imaging the ovaries and the fallopian tubes from thesigmoid colon.

It will be appreciated that the cameras 600 of the present invention mayalso be moved manually, both linearly, into the body lumen androtationally, around its longitudinal axis, preferably while theposition-tracking device 635 (FIG. 34A) registers its position.

It will be appreciated that a camera with a single block or a singledetecting unit may also be used.

Example 10

Referring further to the drawings, FIGS. 35A-35Q schematicallyillustrate radioactive-emission measuring cameras 600, adapted for theesophagus, in accordance with preferred embodiments of the presentinvention.

FIG. 35A schematically illustrates the basic radioactive-emissionmeasuring camera 600, for the esophagus. The camera 600 includes anextracorporeal portion 610, which comprises a control unit, and anintracorporeal portion 630, having proximal and distal ends 631 and 633,with respect to an operator (not shown). A flexible cable 620 connectsbetween them.

The control unit 610 may include control buttons 612 and possibly adisplay screen 614, and may provide connections with a computer station.It may receive power from a grid or be battery operated. The controlunit 610 may further include a computer or a microcomputer.

The intracorporeal portion 630 is constructed essentially as the camera10 of FIG. 23C and FIGS. 20A-20H, and specifically, FIG. 20H.

Thus, the intracorporeal section 630 defines a cylindrical coordinatesystem of x;r, wherein x is the longitudinal axis. The plurality ofblocks 90 along the intracorporeal portion 630 is housed in an internalstructure 21.

Each of the blocks 90 is adapted for the windshield-wiper likeoscillatory motion, around the radius r, as denoted by the arrows 50.The oscillatory motions may be synchronized in an antipodal manner, soas to be diametrically opposed to each other, as shown hereinabove inFIGS. 20B and 20E, by the arrows 54, and as shown hereinabove in FIGS.20C and 20F by the arrows 56. However, other motions are also possible.For example, the blocks 90 may move together, or independently. It willbe appreciated that an odd number of blocks 90 is also possible.

Additionally, the internal structure 21 is adapted for rotational motionaround the x-axis, in the direction of ω, wherein after each step ofoscillatory motion at a certain orientation of ω, the internal structure21 rotates by a step to a new orientation of ω, and the oscillatorymotion is repeated.

As a consequence, a plurality of broken line traces 59 are formed, inthe body section 230, as seen in FIG. 35J.

Preferably, the controller or the computer registers the locations andorientations of each detecting unit or block and correlates themeasurements with the corresponding positions and orientations.

A position-tracking device 635 may also be used, for providinginformation regarding the position of the camera relative to a knownreference.

It will be appreciated that the camera 600 may include detecting units12 rather then blocks 90.

Preferably, the overall structure 20 remains stationary, and has anexternal surface, which is substantially transparent to nuclearradiation.

A ball bearing 632 may be used at the connecting point with the cable620, to enable the rotational motion.

The intracorporeal section 630 may further include dedicated electronics634 and motion providers 636, such as miniature motors and motiontransfer systems, as known. Alternatively, the motion may be transferredvia the cable 620.

FIGS. 35B and 35C schematically illustrate side and distal views,respectively, of the radioactive-emission measuring camera 600, for theesophagus, having an ultrasound imager 640 at its distal tip 633. Theultrasound imager 640 may provide a structural image which may becorrelated with the functional image. Additionally, it may be used forproviding the size and location of the relevant organ for modeling.Furthermore, it may be used for providing attenuation correction to theradioactive emission measurements.

FIGS. 35D and 35E schematically illustrate side and distal views,respectively, of the radioactive-emission measuring camera 600, for theesophagus, having an MRI imager 642 at its distal tip 633. The MRIimager 642 may provide a structural image which may be correlated withthe functional image. Additionally, it may be used for providing thesize and location of the relevant organ for modeling. Furthermore, itmay be used for providing attenuation correction to the radioactiveemission measurements.

FIGS. 35F-35I schematically illustrate the radioactive-emissionmeasuring camera 600, for the esophagus, having a block 90 at its distaltip 633. The block 90 at the distal tip is also adapted for oscillatorymotion, but about the x-axis, as seen by an arrow 53. When combined withthe rotational motion around the x-axis, it produces traces 55 in theshape of a star, in the body section 230, as seen in FIG. 35K.

FIGS. 35L-35Q schematically illustrates the radioactive-emissionmeasuring camera 600, for the esophagus, having a block 90 at its distaltip 633, adapted for a deployed and a retracted position, and foroscillatory motion about the x-axis, when deployed. The camera 600further has the ultrasound imager 640 at its distal tip 633, as a ring,similarly having a deployed and a retracted position.

FIGS. 35N-35P illustrate the block 90 deployed, and the ultrasoundimager 640 retracted. In this manner, the ultrasound imager 640 does notobstruct the oscillatory motion of the block 90 at the distal tip 633.

FIG. 35Q illustrates the block 90 retracted and the ultrasound imagerdeployed so the block 90 does not obstruct the view of the ultrasoundimager. It will be appreciated that the ultrasound image is to be takenonce, from the distal tip 633, while the radioactive-emissionmeasurements are to be taken at a plurality of orientations, from thedistal tip 633.

FIGS. 36A and 36B schematically illustrates the body section 230,showing an esophagus 650. The radioactive-emission measuring camera 600for the esophagus (FIGS. 35A-35Q), is adapted for oral insertion,through a mouth 652, and is further designed for identifyingpathological features in a neck area 654, for example, as relating tothe vocal cords, the thyroid gland, the submandibular glands.Additionally, it is designed for identifying pathological features inthe trachea 656, the lungs 658, the heart 660, the breasts, the stomach662, the pancreas 664, and the liver 666, as well as other relevantorgans and glands, for example, the lymph glands.

The camera system of the present invention allows imaging of internalorgans from a close proximity. Additionally, it is particularlyadvantageous for overweight people and for women with large breasts, forwhom extracorporeal imaging, for example, extracorporeal cardiac imagingby nuclear emission measurements, is ineffective, because of losses inthe tissue.

For cardiac imaging, the radiopharmaceuticals associated with the cameraof FIGS. 35A-35Q may be Myoview™ (technetium Tc-99m tetrofosmin), acardiac imaging agent, of GE Healthcare, GE Medical Systems,http://www.gehealthcare.com/contact/contact_details.html#diothers.Alternatively, it may be Cardiolite (Sestamibi radiolabeled withTc-99m), of DuPont,http://www1.dupont.com/NASApp/dupontglobal/corp/index.jsp?page=/content/US/en_US/contactus.html.It will be appreciated that other agents may be used, as known, forother relevant organs, for example, for the detection of canceroustissue or other pathologies.

In accordance with the preferred embodiment of the present invention,cardiac imaging is performed with Teboroxime, for example, formyocardial perfusion imaging.

It will be appreciated that the radioactive-emission measuring camera600, for the esophagus of the present invention may also be used inparallel with the cardiac camera system 500 of Example 12, describedhereinbelow.

Example 11

Referring further to the drawings, FIGS. 37-39 schematically illustratethe body section 230, as a heart, which includes the region-of-interest200, associated with the organ 215, being the heart, which includes anaorta 242, a left atrium 244 and a right atrium 246.

FIG. 38 schematically illustrates a second, inner region-of-interest200′, associated with the aorta 242.

Similarly, FIG. 39 schematically illustrates a second, innerregion-of-interest 200′, associated with the left atrium 244.

Referring further to the drawings, FIGS. 40-52E schematically illustratea cardiac camera system 500, in accordance with a preferred embodimentof the present invention.

FIGS. 40-45 schematically illustrate the basic components of the cardiaccamera system 500, in accordance with embodiments of the presentinvention. These include an operator computer station 510, a chair 520,and a radioactive-emission camera assembly 530.

As seen in FIG. 43, computer station 510 may be further adapted forinput of an ultrasound imager 535, for example, a handheld ultrasoundimager 535, possibly with a position-tracking device 537, or a 3-Dultrasound imager. The data provided by the ultrasound imager 535 may beused in the modeling of the heart. Preferably, the data of theultrasound imager may be co-registered with the radioactive emissionmeasurements, on the same frame of reference, for providingco-registration of structural and functional images. It will beappreciated that the imager 535 may be an MRI imager.

A problem in cylindrical volumes, when viewed along the periphery of thecylinder is that the innermost information is blocked by the concentricinformation around it. Thus, it is often advisable to obtain views fromthe bases of the cylinder.

FIG. 44 schematically illustrate a camera 530A, which includes shouldersections 530B, for viewing the heart essentially from a base of thecylindrical volume, in accordance with embodiments of the presentinvention.

FIG. 45 schematically illustrate cameras 530B, formed as shouldersections for viewing the heart essentially from a base of thecylindrical volume, in accordance with an alternative embodiment of thepresent invention.

Views from the shoulders, either as in FIG. 44 or 45 providesinformation not blocked or hidden by the chest.

It will be appreciated that the design of cameras 530B is possiblebecause of the small size of the blocks 90 relative to the contour or ofthe body section 230.

FIG. 46 schematically illustrates the chair 520 and the camera assembly530, arranged for operation, in accordance with a preferred embodimentof the present invention. Preferably, the chair 520 is in a partialreclining position, and the camera assembly 530 is designed to face it,opposite the chest of a person sitting on the chair 520. Preferably, thecamera assembly 530 includes a housing, operative as the overallstructure, which is substantially transparent to radioactive emission.Alternatively, a skeleton, which is open on the side facing a patient,may be used as the overall structure.

It will be appreciated that another chair or a bed may be used ratherthan the chair 520. Alternatively, the patient may be standing.

FIGS. 47-48 schematically illustrate possible inner structures of thecamera assembly, in accordance with preferred embodiments of the presentinvention.

FIG. 47 schematically illustrates the inner structure of the cameraassembly 530, showing the overall structure 20, the parallel lines ofassemblies 92, possibly of an even number, each with a dedicated motionprovider 76 and a dedicated secondary motion provider 78, and the rowsof blocks 90, possibly arranged in pairs, along the assemblies 92.

The camera assembly 530 defines an internal frame of reference 80, whileeach assembly 92 has a reference cylindrical coordinate system of x;r,with rotation around x denoted by ω and rotation around r denoted by φ,wherein the oscillatory motion about r is denoted by the arrow 50.

Preferably, the motion of the camera assembly 530 corresponds to thatdescribed hereinabove, with reference to FIGS. 20A-20H and 22A-22H, asfollows:

The plurality of blocks 90 is adapted for the windshield-wiper likeoscillatory motion, around the radius r, as denoted by the arrow 50. Theoscillatory motions may be synchronized in an antipodal manner, so as tobe diametrically opposed to each other, as shown hereinabove in FIGS.20B and 20E, by the arrows 54, and as shown hereinabove in FIGS. 20C and20F by the arrows 56. However, other motions are also possible. Forexample, the blocks 90 may move together, or independently. It will beappreciated that an odd number of blocks 90 is also possible.

Furthermore, the plurality of assemblies 92 are preferably arranged inparallel, and their rotational motions, around the x-axis, in thedirection of ω, may also be synchronized in an antipodal manner, so asto be diametrically opposed to each other, as shown hereinabove, in FIG.22C, by arrows 62, and as shown hereinabove in FIG. 22G, by arrows 64.However, other motions are also possible. For example, the assemblies 92may move together, or independently. It will be appreciated that an oddnumber of assemblies 92 is also possible.

Thus, the resultant traces are a large plurality of the broken linetraces 59, as seen hereinabove, with reference to FIGS. 22D and 22H, onthe chest of the patient.

In accordance with the present example,

i. The different blocks 90 provide views from different orientations;

ii. The different blocks 90 may change their view orientations;

iii. The different assemblies 92 provide views from differentorientations; and

iv. The different assemblies 92 may change their view orientations.

The operational manner of the camera 530 is described hereinbelow withreference to FIG. 23D, for the at least two assemblies 92.

Preferably, the motions of the blocks 90 and of the assemblies 92 arecontained within the overall structure 20, so that the external surfaceof the camera assembly 530 remains stationary, wherein the externalsurface of the camera assembly 530 is substantially transparent tonuclear radiation. Alternatively, the overall structure may be askeleton, open on the side facing the patient.

It will be appreciated that the oscillatory motions need not besynchronized in an antipodal manner. Rather, the blocks 90 may movetogether, or independently. It will be appreciated that an odd number ofblocks 90 is also possible.

It will be appreciated that camera 530 may include a plurality ofassemblies 92, which are not parallel to each other. For example, theassemblies 92 may be at right angles to each other, or at some otherangle. It will be appreciated that the assemblies 92 may includedetecting units 12 rather then blocks 90, for example, as in the camera10 of FIGS. 20A-20G.

FIG. 48 schematically illustrates a section 531 of the camera assembly530, showing the inner structure thereof, in accordance with anotherembodiment of the present invention. Accordingly, the camera assembly530 may include the overall structure 20, and a single one of theassemblies 92, within the overall structure 20, having the dedicatedmotion provider 76, the dedicated secondary motion provider 78, and therows of blocks 90. Additionally, in accordance with the presentembodiment, the camera assembly 530 includes a tertiary motion provider77, for sliding the assembly 90 laterally, in the directions of thearrow 75, along the chest of the patient (not shown). In this manner,imaging of the chest may be performed with the single assembly 92.

FIGS. 49A and 49B schematically illustrate the assembly 92 and the block90, in accordance with a preferred embodiment of the present invention.In essence, the assembly 92 is constructed in a manner similar to thecamera 10 of FIGS. 20A-20H, and specifically FIG. 20H, and according toFIG. 23D, hereinabove.

Thus the assembly 92 includes a row of at least two blocks 90, eachadapted for oscillatory motion about r. The blocks 90 are arrangedwithin the internal structure 21.

A motor 88 and a shaft 85 form the motion provider 76, while a secondarymotor 86 and a secondary shaft 84 form the secondary motion provider 78,for the oscillatory motion about r. A plurality of motion transfersystems 74, for example gear systems, equal in number to the number ofblocks 90, transfer the motion of the secondary motion provider 78 tothe blocks 90. The motion transfer systems 74, for example, of gears,make it possible to provide the row of blocks 90 with any one ofparallel oscillatory motion, antipodal oscillatory motion, orindependent motion, depending on the gear systems associated with eachblock 90. It will be appreciated that other motion transfer systems, asknown, may be used.

It will be appreciated that detecting units 12 may be used in place ofblocks 90.

In accordance with the present example, adjacent blocks 90A and 90B maymove in an antipodal manner and adjacent blocks 90C and 90D may move inan antipodal manner, while adjacent blocks 90B and 90C may move inparallel. It will be appreciated that many other arrangements aresimilarly possible. For example, all the pairing combinations of theblocks 90 may move in an antipodal manner, all the blocks 90 may move inparallel, or the blocks 90 may move independently. It will beappreciated that an odd number of blocks 90 may be used in the assembly92.

FIG. 50 schematically illustrates the block 90, in accordance with apreferred embodiment of the present invention. The block 90 includes aframe 93, which houses the detector material 91, which is preferablypixelated, and the collimators 96. Additionally, the frame 93 housesdedicated electronics 97, preferably on a PCB board 99. Furthermore,where several modules of the detector material 91 need to be used, astructural element 89 may be provided to hold the different modules ofthe detector material 91 together. It will be appreciated that a singlepixel detector may be used. Alternatively, a single module of apixelated detector may be used. Alternatively, the block 90 may beconstructed as any of the examples taught with reference to FIGS.17A-17N, or as another block, as known.

The dimensions, which are provided in FIG. 50, are in mm. It will beappreciated that other dimensions, which may be larger or smaller, maysimilarly be used.

FIG. 51 schematically illustrates the cardiac model 250, in accordancewith a preferred embodiment of the present invention. The cardiac model250 includes the volume U, for example, as a cylinder, and theanatomical constraints AC. The rows of blocks 90 are arranged around thevolume U, as permissible by the anatomical constraints AC.

FIGS. 52A-52E schematically illustrate the blocks 90, arranged forviewing the cardiac model 250, in accordance with a preferred embodimentof the present invention.

In FIG. 52A, the block 90 is shown with the frame 93, which houses thedetector material 91, which is preferably pixelated, and the collimators96. Additionally, the frame 93 houses the dedicated electronics 97, onthe PCB board 99.

In FIG. 52B, fields of view 98 of the blocks 90 are seen for a situationwherein adjacent blocks 90A and 90B move in an antipodal manner, whileadjacent blocks 90B and 90C move in a nearly parallel manner. The figureillustrates that when moving in an antipodal manner, the blocks 90 donot obstruct each other's field of view 98. Yet, when moving in aparallel manner, or a near parallel manner, obstruction may occur.

A similar observation is made by FIG. 52C, wherein the adjacent blocks90B and 90C move in an antipodal manner, while the adjacent blocks 90Aand 90B move in a near parallel manner.

Again, it will be appreciated that many other arrangements are similarlypossible. For example, all the pairing combinations of the blocks 90 maymove in an antipodal manner, all the blocks 90 may move in parallel, orthe blocks 90 may move independently. It will be appreciated that an oddnumber of blocks 90 may be used in the assembly 92.

FIG. 52D illustrates possible dimensions for the cardiac model 250. Thedimensions are in mm. It will be appreciated that other dimensions aresimilarly possible. Furthermore, it will be appreciated that the model250 may be based on general medical information of the organ 215 andcommon pathological features associated with it. Additionally, the modelmay be based on information related to a specific patient, such as age,sex, weight, and body type. Furthermore, a structural image, such as byultrasound or MRI, may be used for providing information about the sizeand location of the heart 215 in relation to the body section 230 (FIG.5A), for generating the model 250.

FIG. 52E schematically illustrates a possible arrangement of the blocks90 for viewing the volume U of the model 250, within the anatomicalconstrains AC. The significance of the present invention, as illustratedby Figures and 52E is that all the blocks maintain a close proximity tothe modeled volume U, and to the region-of-interest, in vivo, even asthey move. This is in sharp contrast to the prior art, for example, astaught by U.S. Pat. No. 6,597,940, to Bishop, et al, and U.S. Pat. No.6,671,541, to Bishop, in which the blocks are fixed within a rigidoverall structure, so that as some of the blocks are placed in closeproximity to the body, others are forced away from the body, and theircounting efficiency deteriorates.

Preferably, the radiopharmaceuticals associated with the camera of FIGS.40-52E may be Myoview™ (technetium Tc-99m tetrofosmin), a cardiacimaging agent, of GE Healthcare, GE Medical Systems,http://www.gehealthcare.com/contact/contact_details.html#diothers.Alternatively, it may be Cardiolite (Sestamibi radiolabeled withTc-99m), of DuPont,http://www1.dupont.com/NASApp/dupontglobal/corp/index.jsp?page=/content/US/en_US/contactus.html.It will be appreciated that other agents may be used.

In accordance with the preferred embodiment of the present invention,esophagus imaging is performed with Teboroxime as theradiopharmaceutical.

It will be appreciated that cardiac imaging, in accordance withembodiments of the present invention relates to the imaging of the wholeheart, or to a portion of the heart, or to blood vessels near the heart,for example, the coronary artery.

Example 12

Referring further to the drawings, FIG. 53 schematically illustrates adual imaging system 700 for radioactive-emissions in tandem with athree-dimensional structural imager, in accordance with a preferredembodiment of the present invention.

The dual imaging system 700 includes a three-dimensional structuralimager 720, preferably, on a structural-imager gantry 722, and aradioactive-emission measuring camera 730, preferably, on a cameragantry 732. A patient 750 may lie on a bed 740, which is adapted formotion into the radioactive-emission measuring camera 730 and thethree-dimensional structural imager 720, on a bed gantry 742.

A control unit 710 controls the operation of the dual system 700,including the three-dimensional structural imager 720, theradioactive-emission measuring camera 730, and the bed 740. The controlunit 710 may also analyze the data.

Alternatively, two control units may be used, one for controlling thethree-dimensional structural imager 720 and another for controlling theradioactive-emission measuring camera 730. It will be appreciated thatthe control system of the radioactive-emission measuring camera 730generally controls the order of the operation of the dual system 700,wherein the radioactive-emission measuring may be performed before orafter the structural imaging.

It will be further appreciated that the radioactive-emission measuringcamera 730 may be configured as an add-on system, adapted for operatingwith an existing structural imager. It may be supplied with a dedicatedsoftware, for example, in a CD format, or with its own control unit,which is preferably adapted for communication with the structural imagercontrol unit.

The three-dimensional structural imager 720 may be, for example, a CT oran MRI, which defines a frame of reference, wherein theradioactive-emission measuring camera 730 is co-registered to the frameof reference.

In this manner, co-registration of functional and structural images ispossible. Additionally, the structural image may be used for providingtissue information for attenuation correction of the functional image,resulting in a more accurate functional image.

The radioactive-emission measuring camera 730 may be constructed as onearc 730A, preferably adapted for viewing a full width of a body from asingle position of the camera 730. Alternatively, theradioactive-emission measuring camera 730 may be constructed as two arcs730A and 730B, which are adapted for viewing a full circumference of abody, from a single position of the camera 730. It will be appreciatedthat the camera 730 may have other geometries, for example, a circle, anellipse, a polygon, a plurality of arcs forming a circle, or a pluralityof sections, forming a polygon, or other shapes.

Preferably, where the camera 730 is adapted for viewing a fullcircumference of a patient, from a single position, the bed 740 isformed as a stretcher, with a sheet 744, which is substantiallytransparent to radioactive emission, for example, of a hydrocarbonmaterial.

FIG. 54 schematically illustrates a cross-sectional view of dual imagingsystem 700 for radioactive-emissions in tandem with a three-dimensionalstructural imager, in accordance with a preferred embodiment of thepresent invention.

Preferably, the gantry 732 of the camera 730 is adapted for verticalmotion, as described by the arrows 734, so as to bring the camera 730closer to the patient 750.

Additionally, the gantry 722 of the three-dimensional structural imager720 may be adapted for rotation, as described by an arrow 724.

The bed 740 is preferably adapted for motion into and out of the camera730 and the three-dimensional structural imager 720.

Preferably, the rate of imaging by the three-dimensional structuralimager 720 and by the radioactive-emission measuring camera issubstantially the same, so the bed moves into the two imagers at aconstant speed.

In accordance with embodiments of the present invention, the camera 730,formed of portions 730A and 730B, as illustrated in FIGS. 53 and 54 mayalso be a radioactive-emission measuring PET camera. Additionally, whilethe patient 750 appears lying, the patient may be sitting standing,lying on the back or lying on the stomach.

It will be appreciated that the body structure that may be imaged may bean organ, such as a heart or a pancreas, a gland, such as a thyroidgland or a lymph gland, blood vessels, for example, the coronary arteryor the pulmonary artery, a portion of an organ, such as an aorta or aleft atrium of a heart, a bone, a ligament, a joint, a section of thebody, such as a chest or an abdomen, or a whole body.

Preferably, the radiopharmaceuticals associated with the camera of thepresent invention be any one of the following:

1. anti-CEA, a monoclonal antibody fragment, which targets CEA—producedand shed by colorectal carcinoma cells—and may be labeled by Tc-99m orby other radioisotopes, for example, iodine isotopes (Jessup J M, 1998,Tumor markers—prognostic and therapeutic implications for colorectalcarcinoma, Surgical Oncology; 7: 139-151);

2. In-111-Satumomab Pendetide (Oncoscint®), designed to target TAG-72, amucin-like glycoprotein, expressed in human colorectal, gastric,ovarian, breast and lung cancers, but rarely in healthy human adulttissues [Molinolo A; Simpson J F; et al., 1990, Enhanced tumor bindingusing immunohistochemical analyses by second generationanti-tumor-associated glycoprotein 72 monoclonal antibodies versusmonoclonal antibody B72.3 in human tissue, Cancer Res., 50(4): 1291-8];

3. Lipid-Associated Sialic Acid (LASA), a tumor antigen, used forcolorectal carcinoma, with a similar sensitivity as anti-CEA monoclonalantibody fragment but a greater specificity for differentiating betweenbenign and malignant lesions (Ebril K M, Jones J D, Klee G G, 1985, Useand limitations of serum total and lipid-bound sialic acidconcentrations as markers for colorectal cancer, Cancer; 55:404-409);

4. Matrix Metaloproteinase-7 (MMP-7), a proteins enzyme, believed to beinvolved in tumor invasion and metastasis (Mori M, Barnard G F et al.,1995, Overexpression of matrix metalloproteinase-7 mRNA in human coloncarcinoma, Cancer; 75: 1516-1519);

5. Ga-67 citrate, used for detection of chronic inflammation (Mettler FA, and Guiberteau M J, Eds., 1998, Inflammation and infection imaging,Essentials of nuclear medicine, Fourth edition, Pgs: 387-403);

6. Nonspecific-polyclonal immunoglobulin G (IgG), which may be labeledwith both In-111 or Tc-99m, and which has a potential to localizenonbacterial infections (Mettler F A, and Guiberteau M J, ibid);

7. Radio-labeled leukocytes, such as such as In-111 oxine leukocytes andTc-99m HMPAO leukocytes, which are attracted to sites of inflammation,where they are activated by local chemotactic factors and pass throughthe endothelium into the soft tissue [Mettler F A, and Guiberteau M J,ibid; Corstens F H; van der Meer J W, 1999, Nuclear medicine's role ininfection and inflammation, Lancet; 354 (9180): 765-70]; and

8. Tc-99m bound to Sodium Pertechnetate, which is picked up by red bloodcells, and may be used for identifying blood vessels and vital organs,such as the liver and the kidneys, in order to guide a surgicalinstrument without their penetration.

Additionally, certain organic materials can replace normal atoms inorganic molecules with radioactive atoms, and thus can be used to labelmetabolism. In general, these are used for PET imaging. However, theycan be used for other nuclear imaging as well. The radionuclides may be,for example:

1. F-18 fluoro-deoxyglucose (FDG)

2. F-18 Sodium Fluoride

2. C-11 methionine

3. Other less common C-11 amino acid tracers, such as:

C-11 thymidine,

C-11 tyrosine,

C-11 leucine

4. N-13 ammonia

5. O-15 water

6. Rb-82 Rubidium Rb-82

7. Cu-62 copper

8. Ga-68 gallium

In accordance with the preferred embodiment of the present invention,the dual imaging and any whole body imaging may be performed withTeboroxime as the radiopharmaceutical.

It will be appreciated that other agents may be used.

FIGS. 55A-55C schematically illustrate possible inner structures of thecamera 730, in accordance with preferred embodiments of the presentinvention.

FIG. 55A schematically illustrates the inner structure of the camera730, showing the overall structure 20 and the parallel lines of theassemblies 92, possibly of an even number, each with the row of blocks90, possibly arranged in pairs. Each of the assemblies 92 preferablyincludes the dedicated motion provider 76, for providing the rotationalmotion around x, and the dedicated secondary motion provider 78, forproviding the oscillatory motion about r in the direction of the arrow50.

The camera 730 defines an internal frame of reference 80, while eachassembly 92 has a reference cylindrical coordinate system of x;r, withrotation around x denoted by ω and rotation around r denoted by φ,wherein the oscillatory motion about r is denoted by the arrow 50.

Preferably, the motions of the assemblies 92 and the blocks 90correspond to those described hereinabove, with reference to FIGS.20A-20H and 22A-22H, as follows:

The plurality of blocks 90 is adapted for the windshield-wiper likeoscillatory motion, around the radius r, as denoted by the arrow 50. Theoscillatory motions may be synchronized in an antipodal manner, so as tobe diametrically opposed to each other, as shown hereinabove in FIGS.20B and 20E, by the arrows 54, and as shown hereinabove in FIGS. 20C and20F by the arrows 56. However, other motions are also possible. Forexample, the blocks 90 may move together, or independently. It will beappreciated that an odd number of blocks 90 is also possible.

Furthermore, the plurality of assemblies 92 are preferably arranged inparallel, and their rotational motions, around the x-axis, in thedirection of ω, may also be synchronized in an antipodal manner, so asto be diametrically opposed to each other, as shown hereinabove, in FIG.22C, by arrows 62, and as shown hereinabove in FIG. 22G, by arrows 64.However, other motions are also possible. For example, the assemblies 92may move together, or independently. It will be appreciated that an oddnumber of assemblies 92 is also possible.

Thus, the resultant traces are a large plurality of the broken linetraces 59, as seen hereinabove, with reference to FIGS. 22D and 22H, onthe skin of the patient.

In accordance with the present example,

i. The different blocks 90 provide views from different orientations;

ii. The different blocks 90 change their view orientations;

iii. The different assemblies 92 provide views from differentorientations; and

iv. The different assemblies 92 change their view orientations.

The operational manner of the camera 730 is described hereinbelow withreference to FIG. 23D, for the at least two assemblies 92.

Preferably, the motions of the blocks 90 and of the assemblies 92 arecontained within the overall structure 20, so that the overall structure20 of the camera 730 remains stationary, wherein the external surface ofthe camera 730 is substantially transparent to nuclear radiation.Alternatively, the overall structure may be a skeleton, open on the sidefacing the patient.

It will be appreciated that the oscillatory motions need not besynchronized in an antipodal manner. Rather, the blocks 90 may movetogether, or independently. It will be appreciated that an odd number ofblocks 90 is also possible.

It will be appreciated that the camera 730 may include a plurality ofassemblies 92, which are not parallel to each other. For example, theassemblies 92 may be at right angles to each other, or at some otherangle. It will be appreciated that the assemblies 92 may includedetecting units 12 rather then blocks 90, for example, as in the camera10 of FIGS. 20A-20G.

FIG. 55B schematically illustrates a section 731 of the camera 730,showing the inner structure thereof, in accordance with anotherembodiment of the present invention. Accordingly, the camera 730 mayinclude the overall structure 20, and a single one of the assemblies 92,within the overall structure 20, having the dedicated motion provider76, the dedicated secondary motion provider 78, and the rows of blocks90. Additionally, in accordance with the present embodiment, the camera730 includes a tertiary motion provider 77, for sliding the assembly 90laterally, in the directions of an arrow 75.

FIG. 55C schematically illustrates an alternative arrangement of theblocks 90 around the volume U of the model 250, wherein each of theblocks 90 is provided with motion around the x-axis, in the direction ofω, and with the oscillatory motion about r, preferably in the y-z plane,as illustrated by the arrow 50. Accordingly, the assemblies 92 need notbe used. Rather, each of the blocks 90 may communicate with two motionproviders which provide it with the two types of motion.

FIGS. 56A and 56B schematically illustrate the assembly 92 and the block90, in accordance with a preferred embodiment of the present invention.In essence, the assembly 92 is constructed in a manner similar to thecamera 10 of FIG. 20H, and according to FIG. 23D, hereinabove.

Thus the assembly 92 includes a row of at least two blocks 90, eachadapted for oscillatory motion about r. The blocks 90 are arrangedwithin the internal structure 21.

A motor 88 and a shaft 85 form the motion provider 76, while a secondarymotor 86 and a secondary shaft 84 form the secondary motion provider 78,for the oscillatory motion about r. A plurality of motion transfersystems 74, for example gear systems, equal in number to the number ofblocks 90, transfer the motion of the secondary motion provider 78 tothe blocks 90. The motion transfer systems 74, of gears, make itpossible to provide the row of blocks 90 with any one of paralleloscillatory motion, antipodal oscillatory motion, or independent motion,depending on the gear systems associated with each block 90. It will beappreciated that other motion transfer systems, as known, may be used.

It will be appreciated that detecting units 12 may be used in place ofblocks 90.

In accordance with the present example, adjacent blocks 90A and 90B maymove in an antipodal manner and adjacent blocks 90C and 90D may move inan antipodal manner, while adjacent blocks 90B and 90C may move inparallel. It will be appreciated that many other arrangements aresimilarly possible. For example, all the pairing combinations of theblocks 90 may move in an antipodal manner, all the blocks 90 may move inparallel, or the blocks 90 may move independently. It will beappreciated that an odd number of blocks 90 may be used in the assembly92.

It will be appreciated that many other cameras and camera systems may beconsidered and the examples here are provided merely to illustrate themany types of combinations that may be examined, in choosing and scoringa camera design, both in terms of information and in terms of secondaryconsiderations, such as rate of data collection, cost, and complexity ofthe design.

Example 13

Brain cancer is the leading cause of cancer-related death in patientsyounger than age 35, and in the United States, the annual incidence ofbrain cancer generally is 15-20 cases per 100,000 people.

There are two types of brain tumors: primary brain tumors that originatein the brain and metastatic (secondary) brain tumors that originate fromcancer cells that have migrated from other parts of the body.

Approximately 17,000 people in the United States are diagnosed withprimary cancer each year; nearly 13,000 die of the disease. Amongstchildren, the annual incidence of primary brain cancer is about 3 per100,000.

Primary Brain Tumors are generally named according to the type of cellsor the part of the brain in which they begin. The most common aregliomas, which begin in glial cells, and of which there are severaltypes, as follows:

Astrocytoma, a tumor which arises from star-shaped glial cells calledastrocytes, which most often arises in the cerebrum in adults, whereas,in children, it occurs in the brain stem, the cerebrum, and thecerebellum;

Brain stem glioma, a tumor that occurs in the lowest part of the brainand is diagnosed in young children as well as in middle-aged adults;

Ependymoma, a tumor most common in middle-aged adults, which arises fromcells that line the ventricles or the central canal of the spinal cord,and also occurs in children and young adults; and

Oligodendroglioma, a rare tumor, which arises from cells that make thefatty substance that covers and protects nerves and usually occurs inthe cerebrum, grows slowly and generally does not spread intosurrounding brain tissue.

Some types of brain tumors do not begin in glial cells. The most commonof these are:

Medulloblastoma, also called a primitive neuroectodermal tumor, a tumorwhich usually arises in the cerebellum and is the most common braintumor in children;

Meningioma, which arises in the meninges and usually grows slowly;

Schwannoma, also called an acoustic neuroma, and occurring most often inadults, it is a tumor that arises from a Schwann cell, of the cells thatline the nerve that controls balance and hearing, in the inner ear;

Craniopharyngioma, a tumor which grows at the base of the brain, nearthe pituitary gland, and most often occurs in children;

Germ cell tumor of the brain, a tumor which arises from a germ cell,generally, in people younger than 30, the most common type of which is agerminoma; and

Pineal region tumor, a rare brain tumor, which arises in or near thepineal gland, located between the cerebrum and the cerebellum.

Certain inherited diseases are associated with brain tumors, forexample, Multiple endocrine neoplasia type 1 (pituitary adenoma),Neurofibromatosis type 2 (brain and spinal cord tumors), Retinoblastoma(malignant retinal glioma), Tuberous sclerosis (primary brain tumors),and Von Hippel-Lindau disease (retinal tumor, CNS tumors). Furthermore,genetic mutations and deletions of tumor suppressor genes (i.e., genesthat suppress the development of malignant cells) increase the risk forsome types of brain cancer.

Additionally, exposure to vinyl chloride is an environmental risk factorfor brain cancer. Vinyl chloride is a carcinogen, used in themanufacturing of plastic products such as pipes, wire coatings,furniture, car parts, and house wares, and is present in tobacco smoke.Manufacturing and chemical plants may release vinyl chloride into theair or water, and it may leak into the environment as a result ofimproper disposal. People who work in these plants or live in closeproximity to them have an increased risk for brain cancer.

Secondary brain cancer occurs in 20-30% of patients with metastaticdisease and its incidence increases with age. In the United States,about 100,000 cases of secondary brain cancer are diagnosed each year.Patients with a history of melanoma, lung, breast, colon, or kidneycancer are at risk for secondary brain cancer.

Brain tumors can obstruct the flow of cerebrospinal fluid (CSF), whichresults in the accumulation of CSF (hydrocephalus) and increasedintracranial pressure (IICP). Nausea, vomiting, and headaches are commonsymptoms. They can damage vital neurological pathways and invade andcompress brain tissue. Symptoms usually develop over time and theircharacteristics depend on the location and size of the tumor.

The first step in diagnosing brain cancer involves evaluating symptomsand taking a medical history. If there is any indication that there maybe a brain tumor, various tests are done to confirm the diagnosis,including a complete neurological examination, imaging tests, andbiopsy.

Referring now to the drawings, FIGS. 57A-57F present the principles ofmodeling, for obtaining an optimal set of views, for a body organ 215,in accordance with embodiments of the present invention.

FIG. 57A schematically illustrates a body section 230, illustrating theorgan 215, being the brain 215. The brain 215 is enclosed within a skull830 and includes:

a cerebellum 802, the part of the brain below the back of the cerebrum,which regulates balance, posture, movement, and muscle coordination;

a corpus callosum 804, which is a large bundle of nerve fibers thatconnect the left and right cerebral hemispheres;

a frontal lobe of the cerebrum 806, which is the top, front regions ofeach of the cerebral hemispheres, and is used for reasoning, emotions,judgment, and voluntary movement;

a medulla oblongata 808, which is the lowest section of the brainstem(at the top end of the spinal cord) and controls automatic functionsincluding heartbeat, breathing, and the like;

a occipital lobe of the cerebrum 810, which is the region at the back ofeach cerebral hemisphere, at the back of the head, and contains thecenters of vision and reading ability;

a parietal lobe of the cerebrum 812, which is the middle lobe of eachcerebral hemisphere between the frontal and occipital lobes, located atthe upper rear of the head, and which contains important sensorycenters;

a pituitary gland 814, which is a gland attached to the base of thebrain that secretes hormones, and is located between the pons and thecorpus callosum;

pons 816, which is the part of the brainstem that joins the hemispheresof the cerebellum and connects the cerebrum with the cerebellum, locatedjust above the medulla oblongata;

a spinal cord 818, which is a thick bundle of nerve fibers that runsfrom the base of the brain to the hip area, through the spine(vertebrae);

a temporal lobe of the cerebrum 820, which is the region at the lowerside of each cerebral hemisphere, located at the sides of the head andcontaining centers of hearing and memory.

The brain 215 may include a pathological feature 213, termed herein anorgan target 213. A region-of-interest (ROI) 200 may be defined so as toencompass the brain 215 and the pathological feature 213.

As seen in FIG. 57B, the region-of-interest 200 of FIG. 57A is modeledas a model 250 of a volume U, and the organ target 213 is modeled as amodeled organ targets HS. Additionally, there are certain physicalviewing constraints, associated with the region-of-interest 200, whichare modeled as anatomical constraints AC. In the present case, the skull830 creates viewing constraints, and generally, imaging the brain isperformed extracorporeally.

Referring further to the drawings, FIG. 58 pictorially illustrates amethod 340 for zooming in on a suspected pathological feature, as aprocess of two or more iterations, in accordance with embodiments of thepresent invention, as follows:

As seen in FIG. 58, the method 340 may be described, pictorially, asfollows:

In I: The region-of-interest 200, associated with the organ 215, such asthe brain 215, is defined for the body section 230.

In II: The model 250 of the volume U is provided for theregion-of-interest 200, possibly with one or several of the modeledorgan targets HS, and within the anatomical constraints AC, forobtaining the optimal set of views for the region-of-interest 200. Theoptimal set of views is then applied to the region-of-interest 200,encompassing the brain 215 of the body section 230.

In III: When the suspected organ target 213 is identified, in vivo, inthe brain 215, by radioactive-emission measurements at the optimal setof views, a second, inner region-of-interest 200′ is defined, encirclingthe suspected pathological feature. For example, if a suspectedpathology 213 is identified in the occipital lobe 810 of the cerebrum,that is, the region at the back of each cerebral hemisphere at the backof the head, the second region-of-interest 200′ is defined so as toencircle the occipital lobe 810 of the cerebrum.

In IV: A model 250′ of a volume U′ is provided for the second, innerregion-of-interest 200′, preferably, with at least one modeled organtarget HS, simulating the suspected organ target 213, for obtaining anoptimal pathology set of views for the region-of-interest 200′. Thesecond, pathology set of views is then applied to the second, innerregion-of-interest 200′ of the body section 230. In the present example,the second, pathology set of views is then applied to the occipital lobe810 of the cerebrum, in vivo.

Referring further to the drawings, FIGS. 59A-60J schematicallyillustrate a camera system 850 for the brain, in accordance with apreferred embodiment of the present invention.

FIGS. 59A-59C schematically illustrate the radioactive-emission camerafor the brain, in accordance with embodiments of the present invention;

Preferably, radioactive-emission camera 850 for the brain is shaped as ahelmet 860, adapted for wearing on a head 862. The helmet 860 ispreferably mounted on a gantry 870, which may be adjustable in thedirections of arrows 872, 874 and 876, for adapting to individualheights and comfort requirements.

Alternatively, no gantry is used, and the helmet 860 may be worndirectly on the head 862, for example, like a motorcycle helmet.

A chair 880 may be provided for the comfort of the patient.

Preferably, the radioactive-emission camera 850 for the brain isoperable with a control unit 890, which may be a desktop computer, alaptop, or the like. The control unit 890 is preferably used both forcontrolling the motions of the detecting units 12, blocks 90 andassemblies 92 of the radioactive-emission camera 850 for the brain andfor analyzing the data.

It will be appreciated that the radioactive-emission camera 850 for thebrain may be supplied merely as the camera helmet 860 and a data storagedevice, such as a CD 892, a disk 892, or the like, containing theappropriate software, for operation with an existing computer, at thesite.

It will be appreciated that the present camera system for the brain mayalso be used as a PET system, for coincident counting.

It will be appreciated that the radioactive-emission camera 850 for thebrain may be operable with a structural imager, as taught by commonlyowned PCT publication WO2004/042546, whose disclosure is incorporatedherein by reference. The structural imager may be a handheld ultrasoundimager, possibly with a position-tracking device, a 3-D imager such asan ultrasound imager, a CT imager, or an MRI imager, as known. The dataprovided by the structural imager may be used for any one or acombination of the following:

i. obtaining accurate dimensional data for modeling the brain 215, astaught with reference to FIGS. 57A-58 and 11-12;

ii. providing attenuation correction for the radioactive-emissions,based on the structural data, as taught by commonly owned PCTpublication WO2004/042546; and

iii. co-registering the functional and structural images, as taught, forexample, by commonly owned PCT publication WO2004/042546.

Referring further to the drawings FIGS. 60A-60K schematically illustrateinner structures of the camera 850 in accordance with severalembodiments of the present invention.

FIG. 60A schematically illustrates the assembly 92, comprising, forexample four of the blocks 90, adapted for oscillatory motion about ther-axis, as illustrated by the arrows 50, and adapted for rotationalmotion about the x-axis, as illustrated by the arrow 62, as taught, forexample, with reference to FIGS. 22A-22H. It will be appreciated thatdetecting units 12 may be used in place of blocks 90.

FIG. 60B schematically illustrates a possible cross sectional view ofthe camera 850 (FIG. 59C), showing an arrangement of the assemblies 92,laterally around the head 862.

FIG. 60C schematically illustrates a top view of the camera 850, showingan arrangement of the assemblies 92, laterally around the head 862. Itwill be appreciated that the number of the blocks 90 may vary around thehead 862.

FIGS. 60D and 60E schematically illustrate other possible crosssectional views of the camera 850, showing arrangements of theassemblies 92, vertically around the head 862.

FIG. 60F schematically illustrates the camera 850 formed as the helmet860, with the assemblies 92, arranged as illustrated by the crosssectional view of FIG. 60E. It will be appreciated that otherarrangements are similarly possible. Preferably, the camera helmet 860includes an overall structure 864. Preferably, the motions of the blocks90 and of the assemblies 92 are contained within the overall structure864.

Preferably, the proximal side of the overall structure 864 with respectto the head 862 (FIG. 59C) is transparent to nuclear radiation.Alternatively, the proximal side with respect to the head 862 is open.

FIG. 60G schematically illustrates another arrangement of the blocks 90around the head 862, wherein the blocks 90 are not arranged inassemblies 92; rather each block 90 moves as an individual body. It willbe appreciated that the detecting units 12 may be used in place of theblocks 90.

FIGS. 60H-60K schematically illustrate possible rotational motions ofthe blocks 90, each of the blocks 90 moving as an individual body forobtaining views of different orientations. As seen in FIG. 60H, theblock 90 rotates around x as seen by an arrow 852 and at each positionaround x, oscillates about x, as seen by an arrow 851. The resultanttraces are seen in FIG. 60I as a star of line traces 854.

Alternatively, as seen in FIG. 60J, the block 90 rotates around y asseen by an arrow 853 and at each position around y, oscillates about x,as seen by the arrow 851. The resultant traces are seen in FIG. 60K, asline traces 855.

The assembly 92 and the block 90, in accordance with a preferredembodiment of the present invention are described in FIGS. 49A and 49B,hereinabove.

Thus the assembly 92 includes a row of at least two blocks 90, eachadapted for oscillatory motion about r. The blocks 90 are arrangedwithin the internal structure 21.

A motor 88 and a shaft 85 form the motion provider 76, while a secondarymotor 86 and a secondary shaft 84 form the secondary motion provider 78,for the oscillatory motion about r. A plurality of motion transfersystems 74, for example gear systems, equal in number to the number ofblocks 90, transfer the motion of the secondary motion provider 78 tothe blocks 90. The motion transfer systems 74, of gears, make itpossible to provide the row of blocks 90 with any one of paralleloscillatory motion, antipodal oscillatory motion, or independent motion,depending on the gear systems associated with each block 90. It will beappreciated that other motion transfer systems, as known, may be used.

It will be appreciated that detecting units 12 may be used in place ofblocks 90.

In accordance with the present example, adjacent blocks 90A and 90B maymove in an antipodal manner and adjacent blocks 90C and 90D may move inan antipodal manner, while adjacent blocks 90B and 90C may move inparallel. It will be appreciated that many other arrangements aresimilarly possible. For example, all the pairing combinations of theblocks 90 may move in an antipodal manner, all the blocks 90 may move inparallel, or the blocks 90 may move independently. It will beappreciated that an odd number of blocks 90 may be used in the assembly92.

It will be appreciated that imaging, in accordance with embodiments ofthe present invention relates to the imaging of the whole brain, or to aportion of the brain, or to blood vessels near the brain, for example,the coronary artery.

Preferably, the radiopharmaceuticals associated with the camera of thepresent invention may be Tc99m-d, 1-hexamethyl propylene amine oxime(1-HMPAO) commercially known as Ceretec by GE-Amersham, or Tc-99m-ECD,commercially known as Neurolite, and made by Bristol Myers Squibb.

The present invention applies to the two types of brain tumors: primarybrain tumors, which originate in the brain and metastatic (secondary)brain tumors that originate from cancer cells that have migrated fromother parts of the body.

Additionally, the primary brain tumors may be gliomas, which begin inglial cells, and of which there are several types, as follows:

Astrocytoma, a tumor which arises from star-shaped glial cells calledastrocytes, and which in adults, most often arises in the cerebrum,whereas in children, it occurs in the brain stem, the cerebrum, and thecerebellum.

Brain stem glioma, a tumor that occurs in the lowest part of the brain,and is diagnosed in young children as well as in middle-aged adults.

Ependymoma, a tumor, most common in middle-aged adults, which arisesfrom cells that line the ventricles or the central canal of the spinalcord and which occurs in children and young adults.

Oligodendroglioma, a rare tumor, which arises from cells that make thefatty substance that covers and protects nerves and usually occurs inthe cerebrum, grows slowly and generally does not spread intosurrounding brain tissue.

Additionally or alternatively, the present invention applies to othertypes of brain tumors, which do not begin in glial cells. The mostcommon of these are:

Medulloblastoma, also called a primitive neuroectodermal tumor, a tumorwhich usually arises in the cerebellum and is the most common braintumor in children.

Meningioma, which arises in the meninges and usually grows slowly.

Schwannoma, also called an acoustic neuroma, and occurring most often inadults, it is a tumor that arises from a Schwann cell, of the cells thatline the nerve that controls balance and hearing, in the inner ear.

Craniopharyngioma, a tumor which grows at the base of the brain, nearthe pituitary gland, and most often occurs in children.

Germ cell tumor of the brain, a tumor which arises from a germ cell,generally, in people younger than 30, the most common type of which is agerminoma.

Pineal region tumor, a rare brain tumor, which arises in or near thepineal gland, located between the cerebrum and the cerebellum.

Additionally or alternatively, the present invention applies to tumorsassociated with certain inherited diseases, for example, Multipleendocrine neoplasia type 1 (pituitary adenoma), Neurofibromatosis type 2(brain and spinal cord tumors), Retinoblastoma (malignant retinalglioma), Tuberous sclerosis (primary brain tumors), and VonHippel-Lindau disease (retinal tumor, CNS tumors), and genetic mutationsand deletions of tumor suppressor genes (i.e., genes that suppress thedevelopment of malignant cells), which increase the risk for some typesof brain cancer.

Additionally or alternatively, the present invention applies to tumorsassociated with exposure to vinyl chloride.

Additionally or alternatively, the present invention applies tosecondary brain cancer, for example, originating from the lungs, thebreasts, or other parts of the body.

It will be appreciated that the present invention further applies toother types brain tumors, which may be malignant or benign, blood clotsin the brain, and other brain pathologies. It will be appreciated thatmany other cameras and camera systems may be considered and the exampleshere are provided merely to illustrate the many types of combinationsthat may be examined, in choosing and scoring a camera design, both interms of information and in terms of secondary considerations, such asrate of data collection, cost, and complexity of the design.

Example 14

Referring further to the drawings, FIG. 61A pictorially illustrates amethod 340 for zooming in on a suspected pathological feature in abreast, as a process of two or more iterations, in accordance withembodiments of the present invention.

As seen in FIG. 61A, the method 340 may be described, pictorially, asfollows:

In I: The region-of-interest 200, associated with the organ 215, such asthe breast 215, is defined for the body section 230.

In II: The model 250 of the volume U is provided for theregion-of-interest 200, possibly with one or several of the modeledorgan targets HS, and within the anatomical constraints AC, forobtaining the optimal set of views for the region-of-interest 200. Theoptimal set of views is then applied to the region-of-interest 200,encompassing the breast 215 of the body section 230.

In III: When the suspected organ target 213 is identified, in vivo, inthe breast 215, by radioactive-emission measurements at the optimal setof views, a second, inner region-of-interest 200′ is defined, encirclingthe suspected pathological feature.

In IV: A second model 250′ of a second volume U′ is provided for thesecond, inner region-of-interest 200′, preferably, with at least onemodeled organ target HS, simulating the suspected organ target 213, forobtaining an optimal pathology set of views for the secondregion-of-interest 200′. The second, pathology set of views is thenapplied to the second, inner region-of-interest 200′ of the body section230.

Alternatively, as seen in FIG. 61B, the method 340 may be described,pictorially, as follows:

In I: The region-of-interest 200, associated with the organ 215, such asthe breast 215, is defined for the body section 230, when compressedbetween two plates 902 and 904, for example, mammograph plates.

In II: The model 250 of the volume U is provided for theregion-of-interest 200, possibly with one or several of the modeledorgan targets HS, and within the anatomical constraints AC, representingthe mammograph plates, for obtaining the optimal set of views for theregion-of-interest 200. The optimal set of views is then applied to theregion-of-interest 200, encompassing the organ 215 of the body section230.

In III: When the suspected organ target 213 is identified, in vivo, inthe organ 215, by radioactive-emission measurements at the optimal setof views, a second, inner region-of-interest 200′ is defined, encirclingthe suspected organ target 213.

In IV: A second model 250′ of a second volume U′ is provided for thesecond, inner region-of-interest 200′, preferably, with at least onemodeled organ target HS, simulating the suspected organ target 213, forobtaining an optimal pathology set of views for the secondregion-of-interest 200′. The second, pathology set of views is thenapplied to the second, inner region-of-interest 200′ of the body section230.

It will be appreciated that this camera system may also be used as aPET.

FIGS. 61A-61B schematically illustrate the modeling of a breast inaccordance with embodiments of the present invention. However, generallythe breast is tested when compressed, as described hereinbelow.

Mammography is currently the most effective method of screening forbreast cancer, for the detection of early non-palpable tumors. Inessence, it involves compressing the breast between two plates, asupport plate and a compression plate, and passing x-rays through thecompressed breast. The compression is desirous both in order to spreadthe breast fatty tissue thin, to reduce its attenuation, and in order tofix the breast tissue, with respect to a frame of reference, so that thex-ray image may be correlated with a surgical tool frame of reference,such as a biopsy needle frame of reference, for guiding the surgicaltool to a suspected location on the x-ray image, without the breasttissue moving between the taking of the x-ray image and the guiding ofthe surgical tool.

Often stereotactic mammography is applied, meaning that the x-ray headis rotated with respect to the plates, so as to provide at least twoviews of the fixed breast, compressed between the plates, from at leasttwo angles, for stereo imaging.

In general, each breast is imaged separately, generally, both in avertical direction and from the side (laterally), preferably,stereotactically. In other words, generally, at least four views of eachbreast are taken, two vertically and two laterally.

A surgical instrument, for example, a biopsy needle, or an ablationdevice, such as a cryosurgery device, an ultrasound ablation device, aknife, or a laser ablation device, may be built onto the mammograph, itsframe of reference correlated with that of the x-ray image.

FIG. 62A schematically illustrates the basic mammograph 900, showing astructural support 929, which defines a frame of reference 80, and whichincludes a support plate 902 and a compression plate 904, thecompression plate 904 being adapted for motion along an arrow 906, so asto compress a breast 909 on the support plate 902.

An x-ray tube 905 is preferably arranged so as to move within a track907, for obtaining x-ray images of the compressed breast 909 from atleast two views, so as to obtain stereotactic viewing, for depthevaluation. A film 901 is preferably arranged under the breast 909, forexample, under the support plate 902, for registering the x-ray image.

Additionally, the mammograph 900 is preferably adapted for rotation, asillustrated by an arrow 908, for compressing a breast from at least twoorientations, for example vertically and laterally.

A surgical tool 903, for example, a biopsy needle 903 or an ablationdevice 903, such as by cryosurgery or laser, or a knife 903, may bebuilt onto the mammograph 900, its frame of reference correlated withthe frame of reference 80, using position tracking devices or a linkagesystem, as known.

FIGS. 62B and 62C schematically illustrate a system 925 of an ultrasoundimager 915, operative with the two plates 902 and 904, in accordancewith embodiments of the present invention. The importance of performingultrasound between two plates, as in the case of x-rays, is that the twoplates fix the breast with respect to the frame of reference 80, and infact, convert the breast to a rigid-like tissue, so that any suspiciousfindings can be located by the surgical tool 903.

In FIG. 62B, the ultrasound imager 915 is arranged to slide along tracks917, for example, on the compression plate 904, while a layer of gel 913or hydrogel 913, between the compression plate 904 and the breast 909ensures good contact for ultrasound imaging. In this manner, anultrasound image, correlated to the frame of reference 80, when thebreast is under compression, may be obtained.

Alternatively, as seen in FIG. 62C the ultrasound imager 915 may bebuilt onto the structural support 929, its frame of reference correlatedwith the frame of reference 80, using position tracking devices or alinkage system, as known.

Referring further to the drawings, FIGS. 63A-63E schematicallyillustrate a radioactive-emission camera 1000 for the breast, foroperation with the mammograph 900 of FIG. 62A, or for operation withanother system, wherein a breast is compressed between two plates, inaccordance with embodiments of the present invention.

FIG. 63A schematically illustrates an external appearance of theradioactive-emission camera 1000, for the breast. The camera 1000 has adriving portion 990 and an imaging portion 980, enclosed in a sheath985. The imaging portion 980 defines cylindrical coordinates 987 of alongitudinal axis along the x-axis, and an r-axis, perpendicular to thelongitudinal axis.

FIGS. 63B-63C schematically illustrate an internal structure of theradioactive-emission camera 1000, for the breast. The imaging portion980 includes several of the blocks 90, for example, between two and sixof the blocks 90, arranged within the sheath 985. It will be appreciatedthat another number, which may be larger or smaller, and which may beodd or even, may be employed.

In FIG. 63B, the motions experienced by the blocks 90 are illustratedwith respect to the cylindrical coordinates 987 of x;r.

A first motion is a rotational motion of all the blocks 90, moving as asingle body, with the shaft 85 and the internal structure 21, around thex-axis, in the direction between +ω and −ω, as illustrated by the arrow52. The first motion is powered by the motor 88.

A second motion is an oscillatory motion of the individual blocks 90,powered by the secondary motor 86, the secondary shaft 84, and themotion transfer link 74, the motion transfer link 74 moving in a linear,sliding motion, as shown by the arrow 71.

At each orientation of the internal structure 21 with respect to ω,around x, the second, oscillatory motion about r takes place,individually by each of the block 90, the oscillatory motion about rbeing between −φ and +φ, as illustrated by the arrow 50, and as taughthereinabove, with reference to FIGS. 20A-20H.

Thus, the overall motion is as illustrated hereinabove, with referenceto FIG. 23C and FIG. 20H.

Further as seen in FIG. 63C, the rotational motion in the direction ofthe arrow 52 is provided by a motor 88 and the shaft 85, which togetherform the motion provider 76. The motor 88 may be an electric motor, forexample, a servo motor. The oscillatory motion in the direction of thearrow 50 is provided by a secondary motor 86, a secondary shaft 84 and amotion transfer link 74. The secondary motor 86 may also be an electricmotor, for example, a servo motor. The secondary motor 86, secondaryshaft 84 and the motion transfer link 74, together, form the secondarymotion provider 78, for the oscillatory motion, in the direction of thearrow 50.

Thus, for the radioactive-emission camera 1000, for the breast:

i. The different blocks 90 provide views from different orientations;and

ii. The different blocks 90 may change their view orientationsindependent of each other.

It is important to point out that during the operation of the camera1000, the sheath 985 of the imaging portion 980 (FIGS. 63A and 63B)remains stationary, while the internal structure 21 (FIG. 63C) rotatesaround the x-axis. The sheath 985 may be formed of a carbon fiber, aplastic, or another material, which is substantially transparent tonuclear radiation.

FIGS. 63D and 63E illustrate further the oscillatory motion of theblocks 90, within the sheath 985, as described by the arrows 50, byshowing the blocks 90 at different positions, along their oscillatorytravel. FIGS. 63D and 63E further illustrate a viewing side 986 and aback side 988 for the camera 1000.

Referring further to the drawings, FIGS. 64A-64M schematicallyillustrate systems 910, which include the radioactive-emission cameras1000 for the breast, operating with systems, in which a breast iscompressed between two plates, for example, as in the mammograph 900, inaccordance with embodiments of the present invention.

Preferably, as seen in FIGS. 64A and 64B, the cameras 1000 are mountedonto the two plates, the compression plate 904, and the support plate902, such that their viewing sides 986 face each other. Preferably, thecameras 1000 are aligned with the x-axis, as seen. Alternatively, thecameras 1000 may be aligned with the y-axis. It will be appreciated thatthe cameras 1000 may be mounted only on one plate, the compression plate904 or the support plate 902.

Additionally, as seen in FIG. 64C, one or several of the cameras 1000may be mounted as edge cameras, for positioning at edges 992 and 994,supplementing the cameras 1000 mounted on the plates, for obtainingviews from the sides of the compressed breast.

An alternative embodiment is illustrated in FIG. 64D, wherein a singleone of the cameras 1000 may be mounted on each of the plates 902 and904, the camera 1000 being adapted for travel along a track 914, in adirection of an arrow 918, by a dedicated motion provider 916, thusproviding the views that a plurality of the cameras 1000 would haveprovided, as illustrated in FIGS. 64A-64B.

It will be appreciated that edge cameras 1000, may be added to theembodiment of FIG. 64D, in a manner similar to that of FIG. 64C.

FIG. 64E schematically illustrates a control unit 890, for controllingthe motions of the blocks 90 (or the detecting units 12, when notarranged in blocks) of the cameras 1000 and for analyzing themeasurements and constructing the images. Preferably, a single controlunit is used both for the x-ray imager, or the ultrasound imager 915, onthe one hand, and the radioactive-emission cameras 1000, on the other.Alternatively, individual control units may be used, one for eachmodality. Alternatively, the system 910 for the breast is provided witha storage device 892, such as a CD or a disk, which contains thesoftware for operating the system 910 for the breast with an existingcomputer on the site. It will be appreciated that the control unit 890may be a PC, a laptop, a palmtop, a computer station operating with anetwork, or any other computer as known.

In accordance with embodiments of the present invention, frames may beprovided for mounting the radioactive-emission cameras 1000 on theplates 902 and 904.

As seen in FIG. 64F, a frame 912 may be provided for either the supportplate 902 or the compression plate 904, designed for accepting thecameras 1000 lengthwise, by inserting the cameras 1000 in holes 926.

Alternatively, as seen in FIG. 64G, the frame 912 may be designed foraccepting the cameras 1000 widthwise.

Additionally, as seen in FIG. 64H, a frame 922 is designed for acceptingthe cameras 1000 widthwise or lengthwise, wherein the frame 922 furtherincludes an edge section 924, for supporting the edge cameras of FIG.64C.

Furthermore, as seen in FIG. 64I, two complementary frames may beprovided, one designed as the frame 922, for accepting the cameras 1000lengthwise (or widthwise) along the plate and for accepting the edgecameras, as illustrated in FIG. 64H, and the other, designed as theframe 912, for accepting the cameras 1000 lengthwise (or widthwise)along the plate.

As seen in FIG. 64J, a frame 923 may be designed for accepting a singleone of the cameras 1000, lengthwise, adapted for sliding widthwise alongthe plate, in a channel 928, by the dedicated motion provider 916.Alternatively, the frame 923 may be designed for accepting the camera1000 widthwise, adapted for sliding lengthwise.

As seen in FIG. 64K, a frame 927 may be designed for accepting a singleone of the cameras 1000, for example, lengthwise, adapted for slidingwidthwise along the plate, in a channel 928, by the dedicated motionprovider 916, wherein the frame 927 further includes the edge section924, for supporting the edge camera 1000 of FIG. 64C.

In accordance with embodiments of the present invention, nuclear imagingby radioactive-emissions, co-registered with x-ray mammography, may beobtained by a method 1010, illustrated in FIG. 64L, in flowchart form,as follows:

in a box 1012: the breast is compressed between the plates;

in a box 1014: an x-ray mammography is performed, as seen in FIG. 62A,preferably from at least two orientations of the x-ray tube 905;

in a box 1016: the cameras 1000 are mounted on the plates, andradioactive-emission measurements are performed;

in a box 1018: where necessary, the surgical tool 903 may be employed,while the breast is still compressed between the two plates.

It will be appreciated that the order of the steps of boxes 1014 and1016 may be reversed.

Preferably, the images of the x-ray mammography and the nuclear imagingare co-registered and analyzed together.

However, it will be appreciated that only nuclear imaging byradioactive-emission measurements may be performed, without x-rayimaging.

Where ultrasound imaging co-registered with nuclear imaging byradioactive-emissions is desired, a method 1020, illustrated in FIG.64M, in flowchart form, applies, as follows:

in a box 1022: a hydrogel layer is placed between one of the plates, forexample, the compression plate 904 and the breast, or a gel is spreadover the breast, so as to serve as an ultrasound interface between theplate and the breast;

in a box 1024: the breast is compressed between the plates;

in a box 1026: the cameras 1000 are mounted on the plates, andradioactive-emission measurements are performed;

in a box 1028: the cameras 1000 are replaced by an ultrasound imager,for example as illustrated in FIG. 62B or 62C, and ultrasound imaging isperformed;

in a box 1030: where necessary, the surgical tool 903 may be employed,while the breast is still compressed between the two plates.

It will be appreciated that the order of the steps 1026 and 1028 may bereversed.

Preferably, the images of the x-ray mammography and the nuclear imagingare co-registered and analyzed together.

Referring further to the drawings, FIGS. 65A-65C schematicallyillustrate a radioactive-emission camera 930, for imaging a breast undervacuum, in accordance with another preferred embodiment of the presentinvention.

As seen in FIG. 65A, the camera 930 includes a vacuum cup 934, shaped asa cone and connected to a vacuum system 932, for creating a vacuum in acavity 935 within. The vacuum in the cavity is used both to stretch thebreast so as to spread the fatty tissue thin and to fix the breasttissue with respect to a frame of reference, so a surgical device may beemployed, where needed, while the breast tissue remains fixed in place.

A vacuum ring 936, for example of natural or synthetic rubber, helpsmaintain the vacuum in the cup 934.

The vacuum cup 934 defines the frame of reference 80 and a plurality ofthe blocks 90 are arranged along the walls 938 of the suction cup 934,each adapted for at least one, and preferably two rotational motions,for example, as illustrated with reference to FIGS. 221-22M and FIGS.22Q-22R, or FIGS. 22N-22P, for imaging a breast in the cavity 935.Alternatively, the blocks 90 may be arranged in the assemblies 92, asillustrated with reference to FIGS. 22A-22H.

A surgical tool may be attached to the camera 930, and correlated to itsframe of reference, for example as taught with reference to FIG. 62B.

The motions of the blocks 90 are preferably automatic, controlled by thecontrol unit 890 (FIG. 64C).

Preferably, the inner walls 938 of the cup 934 are substantiallytransparent to radioactive emission.

FIG. 65B schematically illustrates an embodiment wherein a vacuumcylinder 934 is used in place of a conical cup, and the blocks 90 arearranged in assemblies 92, for example, as illustrated with reference toFIGS. 16E and 24A-24H.

FIG. 65C schematically illustrates an embodiment wherein the vacuumcylinder 934 is used, and a single one of the assemblies 92 is arrangedfor traveling around the cylinder 934, in the direction of an arrow 940,by a motion provider 942.

Referring further to the drawings, FIGS. 66A-66F schematicallyillustrate a radioactive-emission camera 950, for imaging the breasts inthe natural state, in accordance with another preferred embodiment ofthe present invention.

As seen in FIG. 66A, the radioactive-emission camera 950, for imagingthe breasts in a natural state, is designed as an extracorporeal unitwhich may be positioned against the breasts, operating as taught withreference to any one of FIGS. 20A-22R. Preferably, theradioactive-emission camera 950, for imaging the breasts is attached toa gantry 952, which may provide adjustments as seen by arrows 954 and956.

Additionally, the patient may be positioned on a chair 960, as seen inFIG. 66B.

The control unit 890 may be used for controlling the motions of theblocks 90 (FIG. 22A-22H or 22I-22R) or the detecting units 12, when notarranged in blocks, and for analyzing the measurements and constructingthe images. Alternatively, the radioactive-emission camera 910 for thebreast is supplied with a storage device 892, which contains thesoftware for operating the radioactive-emission camera 910 for thebreast with an existing computer on the site. It will be appreciatedthat the control unit 890 may be a PC, a laptop, a palmtop, a computerstation operating with a network, or any other computer as known.

FIG. 66D schematically illustrates a woman 970 being examined by theradioactive-emission camera 950, when seated on the chair 960. It willbe appreciated that the examination may also be conducted when the woman970 is standing or lying on a bed.

FIG. 66E schematically illustrates the inner structureradioactive-emission camera 950 in accordance with a preferredembodiment of the present invention. FIG. 66E shows the overallstructure 20, the parallel lines of assemblies 92, possibly of an evennumber, each with a dedicated motion provider 76 and a dedicatedsecondary motion provider 78, and the rows of blocks 90, possiblyarranged in pairs, along the assemblies 92.

The camera 950 defines the frame of reference 80, while each assembly 92has a reference cylindrical coordinate system of x;r, with rotationaround x denoted by the arrow 62 and oscillatory motion about r, denotedby the arrow 50.

FIG. 66F schematically illustrates the model 250 of the two breasts,modeled as the volumes U, and the anatomical constraints associated withthem, for determining an optimal set of views for radioactive-emissionmeasurements.

It will be appreciated that imaging, in accordance with embodiments ofthe present invention relates to the imaging of the whole breast, or toa portion of the breast, the armpits near the breasts, (and) or the twobreasts.

Preferably, the radiopharmaceuticals associated with theradioactive-emission camera for the breast may be Tc-99m bound toSestamibi, a small protein molecule, made for example, by Bristol MyersSquibb, and marketed as Miraluma, used widely for breast cancerdetection.

The present invention applies to detecting and differentiating betweenvarious types of breast disorders, for example as illustrated in FIG.66G, hereinabove, as follows.

i. fibroadenomas 8, which are fibrous, benign growths in breast tissue.

ii. cysts 9, which are fluid-filled sacs and may disappear sometimes bythemselves, or a doctor may draw out the fluid with a needle.

iii. a breast abscess 11, which is a collection of pus, resulting froman infection.

iv. fibrocystic breast disease 13, which is a common conditioncharacterized by an increase in the fibrous and glandular tissues in thebreasts, resulting in small, nodular cysts, noncancerous lumpiness, andtenderness, wherein treatment of the cysts may be all that is needed.

v. a tumor 15, which may be precancerous or cancerous, and which usuallyshows up as a white area on a mammogram even before it can be felt. Incases where the tumor 15 is cancerous, it may appear as a white areawith radiating arms. A cancerous tumor 15 may have no symptoms or maycause swelling, tenderness, discharge from the nipple 4, indentation ofthe nipple 4, or a dimpled appearance 17 in the skin over the tumor.

Additionally, the present invention applies to detecting various typesof breast cancers, such as:

i. ductal cancer, which affects the cells of the ducts;

ii. lobular cancer, which begins in the lobes or lobules of the breast;and

iii. inflammatory breast cancer, which is an uncommon type of breastcancer and causes the breast to be warm, red, and swollen.

It will be appreciated that the present invention further applies toother types breast disorders, which may be cancerous, precancerous, orbenign.

Additionally or alternatively, the present invention applies tosecondary breast cancer, for example, originating from the lungs, orother parts of the body.

Furthermore, the radioactive-emission camera for the breast may bedesigned for and used on a single breast or designed for and usedsimultaneously on the two breasts.

It will be appreciated that although breast cancer in men and childrenis rare, the present invention may be used for the detection of breastcancer in men and children as well.

Overall Camera Performance

The following section reviews the overall camera performance fordifferent camera designs and illustrates configurations which conform tobody contours, so as to be as close as possible to the anatomicalconstraints (FIG. 5B). Additionally, the importance of distance betweenthe organ target 213 and the detecting block 90 is explained. The cameraperformance is considered with respect to the following:

i. detecting efficiency;

ii. acquisition time;

iii. spatial resolution;

iv. wasteful viewing, in regard to ordinary gamma cameras;

v. adjustable design;

vi. independent viewing by each block or detecting unit;

vii. criteria for camera design;

viii. experimental results.

i. Detecting Efficiency

Referring further to the drawings, FIGS. 67A and 67B schematicallyillustrate the solid angle by which the radiation emission source 213“sees” the detecting block 90. At a distance of R1, the solid angle isβ1 and at the distance of R2, the solid angle is β2, wherein an inverserelation exists between R1 and R2 and β1 and β2, such that when R2>R1then β1>β2.

Furthermore, for the detecting block 90 of an area πr², at a distance Rfrom a point source, the detecting efficiency is a function of the ratioof the detecting area πr² to the area of the sphere 4πR², so as tobehave as a function of r²/R². Thus, for the detecting block 90 of afixed detecting area, as the distance R from the source 213 increases,the detecting efficiency decreases, proportionally to R².

It will be appreciated that a similar analysis is valid for thedetecting unit 12, on a pixel basis, as well.

ii. Acquisition Time

A related issue is the acquisition time, for statistically meaningfulresults. Radioactive emission may be described by the Poissondistribution, for which the counting error for N counts is described byN^(1/2). For example, when 10,000 counts have been detected, thecounting error is 10,000^(1/2), or 100, which is 1% of N. Where it isdesired to obtain data at a predetermined level of accuracy, a minimallevel of counts must be obtained. Thus, for an accuracy level of 1%,10,000 counts must be obtained; for an accuracy level of 0.1%, 1,000,000counts must be obtained, and so on.

Yet, when the distance R between the source 213 and the detecting block90 is increased, the counting efficiency falls proportionally to R² andthe number of counts per minutes falls proportionally to R², and so theacquisition time required to reach a predetermined number of counts, fora predetermined accuracy level, increases proportionally to R².

iii. Spatial Resolution

Referring further to the drawings, FIGS. 68A-68B schematicallyillustrate the effect of the distance R on the spatial resolution.

As seen in FIG. 68A, the organ target 213 has a radius q, which may be,for example, of the order of magnitude of the radius r of the detectingblock 90, so that q˜r. The organ target 213 may have a distribution ofactivity, for example, a high-level portion 213A, a medium-levelradiation portion 213B, and a relatively low-level radiation portion213C.

As seen in FIG. 68B, given, for example, a 3×3 pixel arrangement and acollection angle β, when the block 90 is very close to the organ target213, such that R1 is substantially zero, and given that q˜r, the organtarget 213 is viewed by practically all the 3×3 pixels, resulting in ahigh-resolution image.

As seen in FIG. 68C, at a distance R2, the organ target 213 is barelyviewed by more than one pixel, resulting in a low-resolution image.

As seen in FIG. 68D, at a distance R3, the organ target 213 is viewed byless than one pixel, resulting in a very low-resolution image.

Thus, the number of pixels in the block 90 provides for a spatialresolution capability. In order for this resolution capability to berealized, however, the distance between the detecting block 90 and theorgan target 213 should be as small as possible.

iv. Wasteful Viewing, in Regard to Ordinary Gamma Cameras

Referring further to the drawings, FIGS. 69A-69D schematicallyillustrate different view arrangements.

FIG. 69A illustrates four blocks 90A, 90B, 90C, and 90D for viewing theorgan target 213, the blocks arranged around the body section 230. Theblock 90A, at the distance R1 from the organ target 213, is as close aspossible to the external surface of the body section 230, such that itis substantially touching it. Therefore, the block 90A is at an optimalviewing position for the organ target 213. The block 90B is at adistance R2 from the organ target 213, where R2>R1, but it is still inposition to view the target 213, from that distance. Therefore, theblock 90B is at a suboptimal position for viewing the organ target 213.The block 90C does not view the organ target 213, yet it does view thebody section 230, so it may also be considered at a suboptimal position.The block 90D does not view the body section 230, so the view of theblock 90D is wasteful, in that it does not provide any informationregarding the body section 230.

As FIG. 69A illustrates, blocks which substantially touch the surface ofthe body section 230 will always provide some information about it. Yetblocks 90 that are distant from the body section 230 may view areasaltogether outside the body section 230, so their contribution iswasteful.

This point is further illustrated in FIGS. 69B-69D, which illustrate theuse of a rigid camera of the prior art, for example, as taught by U.S.Pat. Nos. 6,597,940 and 6,671,541, both to Bishop et al. As may beunderstood from FIG. 69B-C, as the blocks 90A and 90B are brought intoclose proximity with the body section 230, blocks 90C, 90D, 90E and 90Fare moved away from it, and their views become suboptimal or evenwasteful. Conversely, as the blocks 90F and 90E are brought into closeproximity with the body section 230, blocks 90D, 90C, 90B and 90A aremoved away from it, and their views become suboptimal or even wasteful

Similarly, as the blocks 90B, 90C, and 90D are brought into closeproximity with the body section 230, the views of blocks 90F and 90Abecome suboptimal or even wasteful

v. Adjustable Designs

Referring further to the drawings, FIG. 71 schematically illustrates anadjustable PET camera 1150, in accordance with embodiments of thepresent invention. The PET camera 1150 is formed of a plurality of theblocks 90, placed substantially on the body section 230. Such a camera,when completely surrounding the body section 230, essentially sees allcoincident emissions coming out of the body, and greatly increases thecounting efficiency for PET.

Referring further to the drawings, FIGS. 72A-72E schematicallyillustrate adjustable cameras 1160 and 1170A-B mounted on adjustableoverall structures, for conforming to contours of the body section 230,in accordance with embodiments of the present invention.

As seen in FIGS. 72A-72B, the cameras 1160 and 1170A-B include hinges90X between the blocks 90, such that the positions of the blocks may beadjusted. Alternatively, as seen in FIG. 72C, several blocks 90 may bearranged in a row to form an assembly 92 and the camera may includehinges 90X between the assemblies 92, such that assemblies 92 may beadjusted. FIG. 72A illustrates the camera 1160 prior to the adjustment,and FIG. 72B illustrates the camera 1160 after adjustment. FIG. 72Cillustrates the camera 1170, as may be used for coincident imaging oranother whole body imaging.

FIG. 72D schematically illustrates the viewing range of the camera 1160,in accordance with the present embodiment.

FIG. 72E schematically illustrates a pictorial view of the camera 1160,of the present embodiment.

Referring further to the drawings, FIGS. 73A-73B schematicallyillustrate adjustable cameras 1100, in accordance with anotherembodiment of the present invention.

FIG. 73A illustrates the blocks 90 mounted on a flexible structure 1180such as cloth, vinyl or the like. Each assembly 90 preferably includes aposition tracking device 1116 and at least one but preferably two ormore motion providers, such as motion providers 1114 and 1112, toprovide the assembly 90 with at least one, but preferably two, three, orpossibly up to six degrees of motion.

FIG. 73B illustrates the blocks 90 linked by chains 1120, to provide theadjustable character.

It will be appreciated that the position tracking device may bemagnetic, electromagnetic, optical, or another device, as known. Forexample, each block 90 may include a Minibird™. Alternatively, twocameras may track the position of each block 90. Alternatively, othertracking methods may be used.

Referring further to the drawings, FIGS. 74A-74B schematicallyillustrate adjustable cameras 1200, in accordance with still anotherembodiment of the present invention. The cameras 1200 are constructed asdetecting modules 1216, which contain blocks 90 or detecting units 12,the detecting modules 1216 being arranged on tracks 1212 which areassociated with a coordinate system 1214. Each of the detecting modules1216 includes an encoder 1218, operative as the position tracking device124 (FIGS. 2 and 3A), as known. The modules move along the tracks 1212by means of a motion provider (not shown) while sending informationregarding their coordinates together with measurements taken to thedata-processing system 126 (FIGS. 2 and 3A).

vi. Independent Viewing by Each Block or Detecting Unit

In accordance with embodiments of the present invention, each block 90of the adjustable camera construction (FIGS. 71-73B) or each detectingunit 12, where single-pixel detecting units 12 are used, may be providedwith at least one, and preferably, two, three, or as many as six degreesof motion such as, for example, rotational motion around the x, y, andz, axis, oscillatory motion about these axes, or translational motionalong these axes. In this manner, each block 90 may be preprogrammed toview each portion of the body section 230, in accordance with somepredetermined schedule. For example, one of the blocks 90 may performoscillatory motion, while an adjacent one of the blocks 90 may performrotational motion. Thus, areas that are known to pose littlesusceptibility to abnormalities may be viewed differently from areasthat are more susceptible to abnormalities. Additionally, active visionmay take place. For example, where something suspicious is viewed, adecision to view it for a longer period of time and to thus obtainbetter data may be made by the data-processing system 126 (FIG. 2), sothat the associated blocks 90 may be instructed to view an area longer.Alternatively, where not enough data has been acquired for the desiredlevel of accuracy, more data may be collected, i.e., the number ofcounts may be increased so as to reduce the margin or error to 1%. Inother words, when using multiple, independent blocks 90 or detectingunits 12, each may spend more time in one region than in another, andeach may spend the time needed to reach a desired level of accuracy.Thus, one block or detector may spend a long time (within apredetermined limit) in one region, while another may spend less timeand move on to another angle and position so as to provide a new view.Similarly, one block 90 or detecting unit 12 may use large steps, whileanother may use fine steps.

The present invention relates to situations that are unlike currentsystems, where the detecting units or blocks are fixed, with respect toeach other, so individual optimization by block or by detecting unit isnot possible.

The reverse is also possible, and a decision to obtain data for lessthan originally intended may be made. Also, cursory imaging may beperformed and, where necessary, a decision may be made to acquire moredata. It will be noted that the blocks along the camera may be designeddifferently and may include different collimators, for the differentportions of the body section 230, such as those taught with reference toFIGS. 17C-17F. For example, the blocks 90 at the edge may havewide-angle collimators and those that are in the central portion of theblocks 90 may have narrow collimators.

vii. Criteria for Camera Design

An overall camera design may be based on the following criteria:

i. a distance from the surface of the body section 230 to the detectingunit 12 or the block 90 which is no greater than 5 cm and, preferably,no greater than 3 cm, and, more preferably, no greater than 2 cm.

ii. wasteful viewing for less than 50% of the viewing of each detectingunit 12 or block 90 and, preferably, less than 30% of the viewing timeand, more preferably, less than 20% of the viewing time.

iii. Substantially no detecting unit 12 or block 90 is positioned so asnot to view the body structure at all.

iv. a collimator solid collection angle of at least 0.0005 steradians,or at least 0.001 steradians, or at least 0.003 steradians, or at least0.005 steradians, or at least 0.01 steradians, or at least 0.03steradians, or at least 0.05 steradians, or at least 0.08 steradians.

v. alternatively, a collimator collection solid angle which isconfigured to view substantially a whole organ, such as a heart, orsubstantially a large portion of the organ.

vi. a block size along the rotational axis, for the block 90, of lessthan 10 cm and, preferably, of less than 6 cm and, more preferably, ofless than 2 mm.

vii. independent motion control for each of the blocks 90, along atleast one rotational axis, preferably along at least two rotational axesand, more preferably, along the three rotational axes and the threetranslational axes.

Wherein a portion of these or all of these may be incorporated into thecamera design.

viii. Experimental Results

Referring to the drawings FIGS. 75A and 75B illustrate Teboroximephysiological behavior, according to Garcia et al. (Am. J. Cardiol.51^(st) Annual Scientific Session, 2002).

Referring further to the drawings, FIGS. 76A-80D illustrate experimentalresults of the camera of the present invention and results of aconventional gamma camera, in terms of resolution, speed, and contrast.In all the experiments, the detectors used were 16×16 pixilated(2.54×2.54 mm in size) CZT arrays made by Imarad, Rehovot, Israel anddriven by the XA controller system made by IDEAS asa., Norway.

Test No 1: Speed and Resolution

Performances of the camera of the present invention and of theconventional gamma camera were compared by equivalent setups, asfollows:

For the camera of the present invention, a center of viewing was at adistance of 150 mm from the collimators' distal end with respect to anoperator. A 5 mili Curie Cobalt 57 line source was placed at a distanceof 1 cm from the center of viewing, so as to be off center for theviewing. A total of 13.5 million photon counts were taken. Acquisitiontime was 49 seconds.

For the conventional gamma camera, a center of rotation was at adistance of 150 mm from the collimators' distal end with respect to anoperator. A 5 mili Curie Cobalt 57 line source was placed at a distanceof 1 cm from the center of rotation, so as to be off center for therotation, and the same number of counts, 13.5 million photon counts, wastaken. Acquisition time was 600 seconds.

Thus, the camera of the present invention was about 12 times moresensitive than the conventional gamma camera.

The image of the source was reconstructed using dedicated reconstructionalgorithms based on the EM method and developed by the inventors. Thereconstruction algorithms used on the conventional unit were OSEM/MLEMbased.

FIG. 76A represents results with the camera of the present invention.

FIG. 76B represents results of the conventional gamma camera.

The measured FWHM (Full Width at Half Maximum) resolutions are shown inTable 1, as follows:

TABLE 1 Resolution FWHM System/Reconstruction (NEMA) [mm] camera of thepresent invention 5.5 conventional gamma camera 10.4

Test No. 2: Resolution as a Function of Scattering Distance

A standard NEMA cylindrical phantom was filled with water, and a 5 miliCurie Cobalt 57 line source of 190 mm in length and 1 mm in diameter wasplaced at its center, as illustrated in FIG. 76C. The cylindricalphantom was placed at a distance R from the distal end of the cameras'collimators. Reconstruction images from two 40-second acquisitions wereperformed and analyzed, wherein the first acquisition was based on equalangle span for all views (Fixed Angle Spans), and the second acquisitionwas based on adjusted angle viewing, for viewing equal sectors of theregion-of-interest (Fixed ROI).

For image reconstruction, a maximal intensity projection (MIP) of thereconstruction without attenuation correction is given in FIG. 76D,based on the combined total of the two acquisitions. The x-z and the y-zplanes each show the line source as a line, and the x-y plane provides across-sectional view of the line.

FIG. 76E illustrates the reconstructed cross-sectional intensity of theline source for the fixed scan angle and Fixed ROI cases, respectively,and for varying distances R from the camera. As expected, the FWHMincreases with increasing R.

FIGS. 76F and 76G schematically show NEMA resolutions in the x and ydirections, respectively, for the fixed-angle span acquisition, whileFIGS. 76H and 76I schematically show NEMA resolutions in the x and ydirections, respectively, for the fixed-ROI acquisition.

Test No. 3: NEMA Three Line Source Acquisition

Three Cobalt 57 line sources were placed inside a standard NEMA phantom,as seen in FIG. 77A.

Viewing coverage was 200 degrees, wherein the distance from the distalend of the collimators to the center of viewing was 150 mm. The totalnet acquisition time was 60 seconds. The images shown in FIGS. 77B-77Dare based on raw reconstruction, without attenuation correction orsmoothing.

After application of a simplistic, model-based attenuation correction,which is acceptable in the case of water as the scattering and absorbingmedium and circular symmetry of an object, the results are shown inFIGS. 77E-77G.

Table 1 below provides resolution numbers for the pre- andpost-attenuation correction results, as follows:

TABLE 1 NEMA resolution FWHM [mm] Point #1 Point #2 (Center) Point #3Without Attenuation Correction X-Direction 5.6 7.7 4.4 Y-Direction 5.4 74.4 With Attenuation Correction X-Direction 6.1 7.6 3.9 Y-Direction 6.37.6 4

Test No. 4: Resolution, Acquisition Time, and Contrast

As shown in FIGS. 78A-78C, two sources, A and B, were placed in acylindrical Perspex phantom, designed to allow the insertion of sourcesof different sizes and intensities.

A comparison of radioactive-emission imaging of the camera of thepresent invention and of a conventional gamma camera was made, and thisincluded image evaluation, sensitivities, and contrast differences.

The cylindrical Perspex phantom was placed with its center at the centerof viewing of the camera. The distance from the distal end of thecollimators to the center of the phantom cylinder was 100 cm.

The total radiation coming from the cylinder, including radiation frombackground, insert A, and insert B, was 930 μCi of Tc-99m. The ratio ofthe amount of radiation from insert A to background radiation was 2:1,while that of radiation from insert B to background radiation was 3:1.Acquisition time was 40 seconds and 1.4 million counts were acquired.The reconstructed images are seen in FIGS. 79A-79C. Both the 2:1 and 3:1Target to Background ratio targets are visible.

The resulting measured contrasts are 2.6:1 and 1.6:1 for the 3:1 and 2:1input contrasts, respectively, in the case of the camera of the presentinvention.

FIG. 79D represents the reconstructed results using the conventionalcamera, for which the acquisition time to reach the 1.4 million countswas 20 minutes. The 3:1 target was reconstructed as a 1.3:1 ratio whilethe 2:1 target was indistinguishable from the background radiation. Themain reason for this loss of contrast is the poor spatial resolution ofthe conventional camera when compared to that of the camera of thepresent invention.

Test No. 5: Reconstruction of Complex Objects—Torso Phantom Acquisition

A standard torso phantom of Anthropomorphic Torso Phantom ModelECT/TOR/P, produced by Data Spectrum Corporation, USA, was provided, asseen in FIG. 80A.

The radioisotope Tc-99m was used as the tracer. The activity of thevarious organs was: Cardio—0.5 mCi, Background—2mCi (0.19 mCi/liter) andLiver—0.23 mCi (0.19 mCi/liter).

An acquisition time of 1.25 minutes was used for the camera of thepresent invention, and an acquisition time of 12.5 minutes was used forthe conventional camera. In both cases, 2.5 M counts were obtained.

FIG. 80B illustrates the results using the camera of the presentinvention, and

FIG. 80C illustrates the results using the conventional gamma camera.

The sensitivity ratio was thus 10:1. The reconstruction is visiblybetter in the case of the camera of the current invention.

FIG. 80D illustrates a reconstructed three-dimensional image of theheart, from the phantom, using the camera of the present invention.

A cold area of 1 cm×1 cm×0.5 cm at a left side of the heart is clearlyseen. Other cold areas are similarly visible.

Test No. 6: Sensitivity Studies

In another exemplary embodiment of the current invention, the

probe system includes multiple blocks of detectors positioned in astructure encircling the imaged area, each is able to rotate about alongitudinal axis substantially parallel to the main axis of thesubject.

In a further example case of 10 such blocks of detectors, each coveringa 40×160 mm section covering about 180-200 deg of the circle around theimaged area, with 10 blocks of collimators each covering 1024 pixelsarranged in a 16×64 pixel matrix, with square collimator opening of2.46×2.46 mm, and a length of 20 mm], the system demonstrated ability todetect about one out of 1500 of the emitted photons from a 2.7 mCi Co⁵⁷point source that was moved about in a 40×30×15 cm volume facing theprobe.

When located in the center of the imaged area (about 150 mm from thedetectors), while the energy window for acquisition was about 5%, andthe detectors were sweeping a wide angular range.

In a further exemplary embodiment, substantially all detectors are ableto simultaneously image the region of interest containing the pointsource and thus obtaining one out of every 500 of the emitted photons.

It is known to the skilled in the art that further opening the energywindow of the detector to about 15%, enables acquisition of about oneout of 250 photons of the photons emission in an experimental settingsimilar to the previous example.

In a further example, each such detector having multiple pixels is ofabout 5 cm wide or more, thus producing a region of interest of at least5 cm in diameter, from which said sensitivity and said resolution isbeing obtained even without the need to move any of the detectors.

In a further possible embodiment of the present invention the width ofeach detector is about 10 cm wide, thus enabling regions of interest ofeven bigger diameters at said resolution and sensitivity with a smallerdetector motion such that bigger objects are continuously viewed by thedetector with only small angular detector motion.

In a further possible embodiment of the present invention the detectorsarray may encircle the imaged subject to the extent of 360 deg, forexample by having two hemi circles from both sides of the subject. Thesensitivity in such case is estimated be about 1 in 125.

In a further exemplary embodiment additional detectors may be positionedto obtain views not perpendicular to the subject's main longitudinalaxis, for example by upper view (e.g. from the shoulders) and abdominalview of the target region (in the case of cardiac mapping). It isestimated that such addition may increase the sensitivity but a factorof about ×2.

As a result, an example embodiment of the present invention is estimatedto be able to image a volume of about 5 cm diameter located about 150 mmfrom the detectors, with energy window of 15%, producing spatialresolution of about 5 mm in approximately 100 sec, with a totalsensitivity of about 1 photons being detected out of 65 emitted.

It will be recognized by a person skilled in the art that a system builtaround the principles of this invention can thus reach the sensitivitynecessary to detect substantially more than one photon from every 100emitted. This result for an imaging system provides more than 100 timebetter sensitivity than commercially available cameras that have asensitivity ranging from substantially from 170 counts/microCurie/minute(or 1 photon in 8500 photons emitted for a Low resolution low energycollimator to about 1 photon in every 15000 emitted for a highresolution medium energy collimator), while maintaining similar energywindows, and potentially similar or better resolution.

Test No. 7: Sensitivity Studies—Grid Point Source

In a further experiment a Co⁵⁷ point source of 2.7mCi activity was usedin order to measure the sensitivity, resolution and geometric accuracyof the probe. A probe composed out of 10 detector columns, eachcontaining detector pixels in a 16×64 pixel arrangement, where eachpixel element had a dimension of 2.46×2.46 mm and being covered by aTungsten collimator matrix with 0.2 mm septal thickness and 20 mm septallength was used to image the point source. The energy window was set at5% FWHM (6 KeV total). A robotic arm was used to move the point sourcewithin a 40×30×15 cm rectangular volume at positions shown in FIG. 70A.FIG. 70B is a diagram showing the error of the reconstructed positionrelative to the nominal position as placed by the robot. It is evidentthat the deviation in position is less than 1 mm for most points andless than 2.5 mm for all points. FIG. 70C shows the FWHM diameter andthe FWTM (Full Width Tenth Maximum) diameter for all points in thevolume. It is noted that the resolutions measured according to the NEMAstandards are substantially under 10 mm throughout the volume and do notexceed 15 mm for all points, a performance equal to or superior toexisting nuclear cameras for similar fields of View. The total netacquisition time for each point was 120 seconds and the typical countrate for, most points (with the exception of positions that could not beviewed by all columns due to mechanical limitations), and the collectednumber of photons was substantially 7-8 million counts for mostpositions fully viewed, yielding a sensitivity of 1 photon out of 1500emitted in the energy window of 5%.

Electrical Scheme

FIG. 143 describes an example of a system that includes multipledetection, amplifications and signal processing paths, thereby avoidingsaturation due to single hot source in space. Gamma-Ray photon (A) ishitting a pixelized CZT crystal. A hit is named ‘Event’. The crystal ispart of a ‘CZT MODULE’ (B) containing the CZT crystal divided into 256pixels and 2 ASICS each receiving events from 128 pixels. The ASIC isOMS ‘XAIM3.4’ made by Orbotech Medical Systems, Rehovot, Israel,together with the CZT crystal. The 2 ASICs share a common output andtransmit the data to ‘ADC PCB’ (C) that handles in parallel 4 ‘CZTMODULES’. Thus, a total of 1024 pixels are presently channeled throughone ADC board. The system is capable of further increasing the acceptedevent rate by channeling every 2 ASICS through a single ADC. The ‘ADCPCB’ transmits the data to the ‘NRG PCB’ (D) that handles in parallel 10‘ADC PCBS’, but could be further replicated should one want to furtherdecrease “dead time”. The ‘NRG PCB’ transmits the data to the ‘PC’ (E)where it is stored.

All in all, in the present embodiment, 40 ‘CZT MODULE’ containing atotal of 10240 pixels are transmitting in parallel to the PC.

The bottle neck, and hence the only constraint, of the system data flowis the ASICS in the ‘CZT MODULE’ and it's connection to the ‘ADC PCB’:

1. An ASIC (128 pixels) can process only one photon hit within 3.5 uSec,or 285,000 events/sec over 128 pixels, i.e. over 2200 events/px/sec-anexceedingly high rate.

2. 2 ASICS share the same output, and hence coincident event output ofthe 2 ASICS in a ‘CZT MODULE’ will cause a collision and informationloss. The duration of an event output from the ASIC is 1 uSec.

General Designs of Detecting Units, Blocks, Assemblies and Cameras

Referring further to the drawings, FIGS. 17A-17H schematicallyillustrate detecting units 12 and blocks 90 that may be considered forpossible camera designs.

FIGS. 17A and 17B schematically illustrate side and top views,respectively, of the basic detecting unit 12 (see also FIG. 1A), havinga detector 91 and a collimator 96, formed as a tube, of a collectionangle δ1.

FIGS. 17C and 17D schematically illustrate side and top views,respectively, of the detecting unit 12, with the collimator 96 formed asa wide angle collimator, of a collection angle δ2.

FIGS. 17E and 17F schematically illustrate side and top views,respectively, of the block 90 (see also FIG. 1B) of the detecting units12, with the collimator 96 formed as a grid, and each of the detectingunit 12 having a collection angle δ3. As few as two or four, and as manyas a hundred or several hundred of the detecting units 12 may beincluded in the block 90.

FIGS. 17G and 17H schematically illustrate side and top views,respectively, of the block 90 of the detecting units 12, with thecollimator 96 formed as a grid, with two sizes of the detecting units12, as follows: small detecting units 94A, of collection angles δ4, atthe center of the grid, and large detecting units 94B, of collectionangles δ5, at the periphery. It will be appreciated that otherarrangements of detecting units of different sizes may be used.

It will be appreciated that a combination of these may be used. Forexample, the block 90 may include wide-angle collimators (FIG. 17C) atthe periphery and normal collimators of 90-degrees (FIG. 17A) at thecenter.

It will be appreciated that the camera 10 may contain blocks 90 and (or)detecting units 12 of different collection angles.

Referring further to the drawings, FIGS. 17I and 17J schematicallyillustrate a detecting unit 12A with an adjustable collimator 96Z, foradjusting the collection angle, in accordance with embodiments of thepresent invention. Preferably, the detecting unit 12A includes thedetector 91 and an adjustor 91A at the bottom of the collimator 96Z.Additionally, the collimator 96Z is formed of a plurality of petalcollimators 96A, 96B, 96C, and so on, wherein the collimator 96Z may bepartially open, as shown in FIG. 17I, or fully open, as shown in FIG.17J, by the action of the adjustor 91A, which may be, for example, arotating knob, controlled by the data-processing system 126 (FIGS. 2,3A). Preferably, the extent of opening of the collimator 96Z isadjustable, so it may be essentially closed, with the petal collimators96A, 96B, 96C and so on substantially vertical with the detector 91,partially open, or fully open, much like a flower.

FIGS. 17K-17N schematically illustrate the block 90, wherein thedetector 91 is a single-pixel scintillation detector, such as NaI(Tl),LSO, GSO, CsI, CaF, or the like, operative with photomultipliers 103.

As seen in FIG. 17K, the block 90, having proximal and distal ends 109and 111, respectively, vis a vis an operator (not shown), is formed ofthe scintillation detector 91, of a single pixel, and the collimators96, to create the detecting units 12. A plurality of photomultipliers103 is associated with the single pixel scintillation detector 91, andwith dedicated algorithms, as known, their output can provide a twodimensional image of the scintillations in the single pixelscintillation detector 91. In essence, this is an Anger camera, asknown.

The distal view 111 of the collimator grid is seen in FIG. 17L.

Two optional proximal views 109 of the photomultipliers 103 are seen inFIGS. 17M and 17N, as a square grid arrangement, and as an arrangementof tubes.

The detector may be a room temperature, solid-state CdZnTe (CZT)detector, configured as a single-pixel or a multi-pixel detector,obtained, for example, from eV Products, a division of II-VICorporation, Saxonburg Pa., 16056, or from IMARAD IMAGING SYSTEMS LTD.,of Rehovot, ISRAEL, 76124, www.imarad.com, or from another source. Adetector thickness τ_(d) may range from about 0.5 mm to about 100 mm,depending on the energy of the radioactive emission and typically about2 mm to about 50 mm, and in some cases about 5 mm to about 30 mm.

Alternatively, another solid-state detector such as CdTe, HgI, Si, Ge,or the like, or a scintillation detector (such as NaI(Tl), LSO, GSO,CsI, CaF, or the like, or a combination of a scintillation detector anda photomultiplier, to form an Anger camera, or another detector asknown, may be used. Additionally, a combination of scintillationmaterials and photodiode arrays may be used.

It will be appreciated that the methods of the present invention applyto pathological features that may be modeled as regions of concentratedradiations, or hot regions, regions of low-level radiation, which isnonetheless above background level, and regions of little radiation, orcold regions, below the background level. However, in general, foridentifying a pathological feature of the heart, they relate to coldregions.

It will be appreciated that the methods of the present inventions may beoperable by computer systems and stored as computer programs oncomputer-readable storage media.

It will be appreciated that the body may be an animal body or a humanbody.

It will be appreciated that the radioactive-emission-camera systems,cameras and methods of the present invention may be used with commonlyowned US Applications 20040015075 and 20040054248 and commonly owned PCTpublication WO2004/042546, all of whose disclosures are incorporatedherein by reference. These describe systems and methods for scanning aradioactive-emission source with a radioactive-emission camera of awide-aperture collimator, and at the same time, monitoring the positionof the radioactive-emission camera, at very fine time intervals, toobtain the equivalence of fine-aperture collimation. In consequence,high-efficiency, high-resolution, images of a radioactive-emissionsource are obtained.

Commonly owned US application 20040054248 and commonly owned PCTpublication WO2004/042546 further disclose various extracorporeal andintracorporeal systems, of radioactive-emission cameras, of relativelywide apertures, associated with position-tracking devices.

It will be appreciated that the radioactive-emission-camera systems,cameras and methods of the present invention may be used with commonlyowned U.S. Pat. No. 6,173,201 to Front, whose disclosure is incorporatedherein by reference, as well as by M. W. Vannier and D. E. Gayou,“Automated registration of multimodality images”, Radiology, vol. 169pp. 860-861 (1988); J. A. Correia, “Registration of nuclear medicineimages, J. Nucl. Med., vol. 31 pp. 1227-1229 (1990); J-C Liehn, A.Loboguerrero, C. Perault and L. Demange, “Superposition of computedtomography and single photon emission tomography immunoscintigraphicimages in the pelvis: validation in patients with colorectal or ovariancarcinoma recurrence”, Eur. J. Nucl. Med., vol. 19 pp. 186-194 (1992);F. Thomas et al., “Description of a prototype emission transmissioncomputed tomography imaging system”, J. Nucl. Med., vol. 33 pp.1881-1887 (1992); D. A. Weber and M. Ivanovic, “Correlative imageregistration”, Sem. Nucl. Med., vol. 24 pp. 311-323 (1994); and Hasegawaet al., U.S. Pat. No. 5,376,795.

These relate to the acquisition of both a functional image of the body,such as a radioactive-emission image, and a structural image, such as anultrasound, an x-ray, or an MRI image, and their co-registration on asingle frame of reference.

In essence, several images may be acquired and co-registered to the sameframe of reference, as follows:

i. a first functional image scan, based for example, on anti-CEAmonoclonal antibody fragment, labeled by iodine isotopes, may beacquired for targeting CEA—produced and shed by colorectal carcinomacells for detecting a pathological feature, such as colorectalcarcinoma;

ii. a second functional image, based for example, onnonspecific-polyclonal immunoglobulin G (IgG), which may be labeled withTc^(99m), may be acquired for locating blood vessels and vitalstructures, such as the heart, or the stomach, co-registered with thefirst functional image and the pathological feature detected on it, inorder to locate the pathological feature in reference to blood vesselsand vital organs; and

iii. a structural image, such as an ultrasound image, may be used forgeneral structural anatomy, co-registered with the first and secondfunctional images, in order to locate the pathological feature inreference to bones and the general anatomic structure.

Thus, a physician may locate the pathological feature in reference tothe blood vessels, vital organs, and the bones, and guide a minimallyinvasive surgical instrument to the pathological feature, while avoidingthe blood vessels, vital organs, and bones. The minimally invasivesurgical instrument may be a biopsy needle, a wire, for hot resection, aknife for cold resection, an instrument of focused energy, to produceablation, for example, by ultrasound, or by laser, an instrument forcryosurgery, an instrument for cryotherapy, or an instrument forbrachytherapy, wherein seeds of a radioactive metal are planted close toa tumor, for operating as a radioactive source near the tumor.

Commonly owned PCT publication WO2004/042546 further discloses that thesurgical instrument may be visible on at least one of the images, forexample, on the structural image, to enable the physician to see theinstrument, the pathological feature, and the surrounding anatomy on thedisplay 129 (FIG. 3A). Additionally, the surgical instrument may beradioactively labeled, to be visible also on the functional image. PCTpublication WO2004/042546 further disclose various extracorporeal andintracorporeal systems, of radioactive-emission cameras, and structuralimagers such as an ultrasound camera or an MRI camera.

Commonly owned U.S. Pat. No. 6,173,201, to Front further discloses amethod of stereotactic therapy, wherein a frame, which includes at leastthree markers, visible on a structural image, is rigidly secured to apatient. The structural image of a region inside the patient's body,which includes a pathological feature and the markers, is acquired. Afunctional image of the pathological feature is then acquired andco-registered with the structural image, to correlate the images to thesame frame of reference. A stereotactic guide is rigidly attached to theframe and is used to guide a surgical instrument, such as a biopsyneedle or a brachytherapy needle, to the pathological feature, withreference to the co-registered images.

Thus the radioactive-emission-camera systems, cameras and methods of thepresent invention may be used together with position tracking devices,for enhanced image acquisition, they may be used together withstructural imager and structural imaging for correlating functional andstructural images, and they may be used for guiding minimally invasivesurgical instruments, such as a biopsy needle, a wire, for hotresection, a knife for cold resection, an instrument of focused energy,to produce ablation, for example, by ultrasound, or by laser, aninstrument for cryosurgery, an instrument for cryotherapy, or aninstrument for brachytherapy.

It will be appreciated that a structural image, such as by ultrasoundmay further be used and in order to provide information about the sizeand location of the body structure 215 for the purpose of creating themodel 250 (FIG. 5A).

It will be appreciated that a structural image, such as by ultrasoundmay further be used and in order to provide information about tissueattenuation, for example, as taught in conjunction by commonly owned PCTpublication WO2004/042546, whose disclosure is incorporated herein byreference. The information may then be used to correct theradioactive-emission measurements.

Active Vision

At present, radioactive-emission imaging of a body structure is athree-stage process. First the radiopharmaceutical is administered. Thenmeasurements are taken at a set of predetermined views, that is atpredetermined locations, orientations, and durations. Finally, the datais analyzed to reconstruct the emission distribution of the volume andan image of the body structure is formed. The imaging process issequential, and there is no assessment of the quality of thereconstructed image until after the measurement process is completed.Where a poor quality image is obtained, the measurements must berepeated, resulting in inconvenience to the patient and inefficiency inthe imaging process.

According to this embodiment, the present invention teaches usingradioactive-emission measurements to define views for furtherradioactive-emission measurements of a body structure, to be performedduring the current measurement process. Specifically, the methods teachanalyzing the previously obtained measurement results to determine whichfurther views are expected to provide a high quality of information. Theanalysis may be based directly on the photon counts obtained for thecurrent or recent measurements and/or on a reconstruction of the bodystructure performed upon the completion of a set of measurements.

The present embodiments address the problem of ensuring that the qualityof data gathered during the measurement process is adequate to provide ahigh quality image. The collected data and/or the image reconstructedfrom the collected data is analyzed the while the measurement process istaking place. Based on the analysis, further views are defined. Sinceeach view is associated with known values of the viewing parameter(s),selecting a view effectively specifies known viewing parameter values.The defined further views thus define a set of viewing parameter values,which are used during the current measurement process in order tocollect data which yields a high-quality reconstruction of the bodystructure.

The following embodiments are of a method for determining further viewsfor the imaging of a body structure, and are not confined to a specificreconstruction algorithm. Further views are preferably defined based onone or more of the following:

1) Detector photon count

2) Geometric properties of the reconstructed body structure

3) Information theoretic measures that quantify the quality of the datafed to the reconstruction algorithm

Each of these criteria is discussed in detail below.

Reference is now made to FIG. 81 which is a self explanatory descriptionof advantageous and disadvanatageous viewing positions according toembodiments of the present invention.

Reference is now made to FIG. 82, which is a simplified flowchart of amethod of performing radioactive-emission measurements of a bodystructure, according to a preferred embodiment of the present invention.In step 200, radioactive-emission measurements of the body structure areperformed at predetermined views, preferably in vivo. Preferably themeasurements are performed for diagnostic purposes. These predeterminedviews are selected prior to the measurement process, based on a model ofthe body structure being imaged. In the model more and less informativeviewing directions have been identified. The predetermined views of step200 preferably include those views expected to be informative, based onan analysis of the model.

Preferably the body structure is all or a portion of: a prostate, aheart, a brain, a breast, a uterus, an ovary, a liver, a kidney, astomach, a colon, a small intestine, an oral cavity, a throat, a gland,a lymph node, the skin, another body organ, a limb, a bone, another partof the body, and a whole body.

In step 210 the radioactive-emission measurements are analyzed.Preferably the analysis includes one or more of:

1) Analyzing detector photon count(s)

2) Analyzing detector photon count rate(s) and rate changes from oneview to another

3) Identifying detector saturation

4) Reconstructing a body structure image from emission measurements

5) Identifying geometric properties of the reconstructed image

6) Applying information-theoretic measures to the reconstructed image

In step 220, further views for measurements are dynamically defined,based on the analysis performed in step 210. Preferably, each of theviews is associated with viewing parameters selected from the groupconsisting of: detector unit location, detector unit orientation,collection angle, and measurement duration. Defining a view consists ofproviding a value for each of the parameters associated with the givenview. The analysis (step 210) and/or dynamic view definition (step 220)may take into account external parameters including: measurementduration, time elapsed from the administration of the pharmaceutical tothe measurement, radiopharmaceutical half life, radioactive emissiontype, and radioactive emission energy.

Each of these analysis techniques, and their application to viewdefinition, is now discussed in turn. While each of the analysis/viewdetermination techniques is discussed as a separate embodiment, multipletechniques may be used together to obtain the desired image quality.

In a first preferred embodiment, a photon count analysis ensures thatthe photon count at a given view yields an acceptable measurement error.As discussed above, the radiative emissions of the body structure beingimaged is a Poisson process. In a Poisson process the Poisson noisegrows inversely to the square root of the number of photons detected. Inother words, if N photons are collected from a given view, the resultingsignal to noise ratio (SNR) equals:SNR=N/√{square root over (N)}=√{square root over (N)}  (12)

The unprocessed detector photon count at a given view thus providessignificant information regarding the quality of the informationobtained at a given view. If the photon count is too low, it may bedesired to continue to collect photons at the currentlocation/orientation in order to obtain a satisfactory SNR.Alternatively, it may be determined that enough photons have alreadybeen collected, and to terminate the current view and move on to thenext view.

The analysis is preferably performed by defining a global or localrequired measurement error, and comparing the square root of theobtained photon count to the required measurement error. Photon countanalysis can be applied to the current and/or previous views. When aphoton count of a current view is found to be too low, the duration ofthe current view is preferably extended in order to obtain the requirederror value. When a photon count of a past view is found to be too low,an emission measurement at substantially the same location andorientation but having a longer duration than previously is preferablyperformed. Alternately or additionally, the collection angle at thegiven location/orientation is preferably increased.

In an additional preferred embodiment, a detector photon count isanalyzed to identify detector saturation at a given view. Preferably,when a detector is determined to have saturated, a new view or views areselected to reinforce those views that have saturated. In an alternatepreferred embodiment, further views are defined to avoidhighly-radiating portions of the body structure.

In a second preferred embodiment, a photon collection rate at a givenview is analyzed to determine if it is within a specified range. In thepreferred embodiment, the photon count rate is used to identify regionsof high or low interest. In prostate imaging, for example, a region ofhigh interest may be identified by a high photon rate, indicative of atumor. In a second example, a region of high interest may be identifiedin heart imaging by a low photon rate, indicative of non-functionaltissues. After one or more areas of high and/or low interest are found,further views are preferably defined by selecting views to concentrateon regions of high interest and/or to avoid regions of low interest. Itis thus possible to zoom in on a suspected pathology without repeatingthe emission measurement process.

In a further preferred embodiment, the analyzing of step 210 includesreconstructing a radioactive-emission density distribution of the bodystructure. Reconstruction may be performed according to any applicabletechnique known in the art. The reconstruction is then used as the basisfor further analysis.

Reconstruction based on the data collected from the predetermined viewsprovides information regarding the quality of information obtained fromthe preceding measurements, and which further views are likely to bemost informative. Selecting new views based on reconstruction isintended to bring us into viewing from the more informative views orcombinations of views.

Reference is now made to FIGS. 83 and 84 a-84 b, which pictoriallyillustrate how different views provide differing types and quality ofinformation. FIG. 3 shows an object 300 shaped as a cylinder with afront protrusion, and having a high-emittance portion (hotspot) 310.Four views of object 300 are shown, which can be seen to providedifferent levels of information. Front views, such as V₁, provide littleinformation regarding the shape of object 300 and have relatively littleattenuation between the detector and hotspot 310. Side views, such asV₂, provide edge information regarding the object shape or profile, andwhen correlated with front views help locate hotspot 310 spatiallywithin object 300. Top views, such as V₃, provide information regardingthe cylinder edge region 320. Finally, rear views, such as V₄, areuninformative about the shape of object 300 and have high attenuationrelative to hot region 310.

FIGS. 84 a and 84 b demonstrate how the proper selection of views mayimprove the quality of information obtained for the body structure, forexample in distinguishing between two regions of interest within a givenvolume.

FIG. 84 a illustrates an object 400 having two high-emission regions ofinterest (ROI), 410 and 420. For clarity the views V_(A) to V_(F) areshown as lines in FIG. 84 a, however in practice they will each have afinite collection angle δ. The position of ROIs 410 and 420 are assumedto have been estimated based on a model of object 400 and/or apreviously performed prescan. A goal of an aspect of the presentinvention is to select an additional new view or views which increasethe information we have regarding the separation of ROIs 410 and 420within object 400.

In simple terms, consider the object as having three regions: ROI 410with intensity I₁, ROI 420 with intensity I₂, and a low-emission region430 between the two ROIs with intensity I₃. The detected intensity at agiven detector is proportional to

I_(n)/r_(ni)²,where I_(n) is the emission intensity of region n and r_(i) is thedistance of region n from detector V_(i).

FIG. 84 b illustrates the added information provided by each of theshown views, V_(A) to V_(F). Views V_(B) and V_(C) collect emissionsfrom all three regions, and are therefore least informative. Views V_(D)and V_(E) collect emissions from only low emittance region 430, andtherefore provide most information regarding the location of each ROIwithin the volume and the separation between ROIs 410 and 420. ViewsV_(A) and V_(F) pass only through a single ROI, and therefore provide anintermediate level of information. It is a goal of the present inventionto determine, while the emission measurements of the body structure aretaking place, that views in the vicinity of V_(D) and V_(E) are highlyinformative, and to add these further views to the measurement process.

A body structure reconstruction can be utilized in several ways todefine further views. A first way is to identify interesting portions ofthe contour and structure of the reconstruction. For example, it is seenin FIG. 83 that top views are informative about edge region 320. Furthertop view measurements will therefore be informative re edge region 320,and may enable defining the edge more accurately.

In a preferred embodiment, the reconstruction is analyzed to identifytextural edges within the reconstruction, and view definition preferablyincludes selecting views at an angle to the textural edges. In thepreferred embodiment, the angle is a substantially sharp angle in orderto provide information regarding the edge.

In another preferred embodiment, the reconstruction is analyzed toidentify volumetric boundaries within the reconstruction, and viewdefinition preferably includes selecting views at an angle to thevolumetric boundaries. It is expected that the defined views willprovide information regarding the boundary and differences insurrounding tissues on either side of the boundary. In the preferredembodiment, the angle is a substantially sharp angle.

Another way to utilize the reconstruction to define further views is toidentify suspected organ targets within the reconstruction, and toselect further view(s) in close proximity to the suspected organtargets. A suspected organ target is typically detected by identifyingportions of the reconstruction whose emission intensity distribution andspatial characteristics are typical of a suspect region.

In a first preferred embodiment, a suspected organ target is defined asa high-emittance portion of the reconstruction. In a second preferredembodiment, a suspected organ target is defined as a low-emittanceportion of the reconstruction.

In the preferred embodiment the further views are used immediately forradioactive-emission measurements. The results of the new measurementsare then used in another analysis to define new further views foradditional measurements. The radioactive-emission measurements may thenbe said to be performed iteratively.

Reference is now made to FIG. 85 a, which is a simplified flowchart ofan iterative method of performing radioactive-emission measurements of abody structure, according to a first preferred embodiment of the presentinvention. In step 500, radioactive-emission measurements of the bodystructure are performed at predetermined views. In step 510, an analysisis performed of the previously performed emission measurements. In step520 a decision is made whether to continue with further measurements. Ifyes, in step 530 further views are defined based on the analysis.Subsequent iterations continue until the decision to end the emissionmeasurement process. After the first iteration, the analysis performedat a given stage may include consideration of all or on part of themeasurements performed during one or more previous iterations, inaddition to the new measurements.

Reference is now made to FIG. 85 b, which is a simplified flowchart of aiterative method of performing radioactive-emission measurements of abody structure, according to a second preferred embodiment of thepresent invention. In the present preferred embodiment, a reconstructionof the body structure is formed in step 505. The analysis step 510 isthen performed utilizing data provided by the reconstruction(s).

Referring again to FIG. 82, preferably, analysis step 210 includesdetermining an accuracy of the reconstruction. Accuracy is preferablydetermined by analyzing the variance of the reconstructions formed overmultiple iterations. Preferably, further views are defined in step 220to concentrate on the region for which higher accuracy is required.Regions of the reconstruction having low variance provide a high degreeof confidence regarding the accuracy of the reconstruction in the givenregion (where a portion may include the entirety of the body structurebeing imaged). Further views may be added to the current measurementsuntil the variance is reduced to a required level.

Preferably, analysis step 210 includes determining a resolution of thereconstruction. Resolution is preferably determined by analyzing thefull width at half maximum (FWHM) of peak values of the reconstruction.The FWHM is given by the distance between points at which thereconstructions reaches half of a peak value. Preferably, further viewsare defined in step 220 to concentrate on the region for which higherresolution is required.

An additional way to define future views using the reconstruction is onan information-theoretic basis. A quality function expressing aninformation theoretic measure is defined. The quality function rates theinformation that is obtainable from the body structure when one or morepermissible views are added to current measurement process. Severalexamples of quality functions based on information-theoretic measuresare discussed in detail below. The quality function is used to ratepotential further views. The measurement process may then continue atthose further views whose addition to the previous views yields a highrating.

Reference is now made to FIG. 86 a, which is a simplified flowchart of amethod for dynamically defining further views, according to a firstpreferred embodiment of the present invention. In step 610 a qualityfunction is provided. The quality function expresses aninformation-theoretic measure which rates the quality of informationobtainable from potential further views. In step 620 a set of furtherviews is selected to maximize the quality function. Preferably theselected further views fulfill certain constraints; for example thefurther views may be selected from a predefined set or may be located inthe vicinity of a region of interest within the body structure.

In the abovedescribed reconstruction-based analyses, the qualityfunction is evaluated independently for a single reconstruction of theemission intensity of the body structure. However, quality functions maybe defined which calculate the score for a given set in relation to oneor more reconstructions and/or emittance models. As is further discussedherein, given an object or class of objects, emittance models may bedevised to reflect expected or typical emission patterns for the givenobject.

For simplicity, the following discussion describes the evaluation ofinformation-theoretic quality functions based on emittance models only.It is to be understood that at least one of the emittance models is areconstruction of the body structure based on past measurements. Anyremaining emittance models are provided externally, and may be based ongeneral medical knowledge or on information gathered during a previousround of emission measurements of the body structure.

Reference is now made to FIG. 86 b, which is a simplified flowchart of amethod for dynamically defining further views, according to a secondpreferred embodiment of the present invention. The current methoddiffers from the method of FIG. 86 a by the addition of steps 605-606.In step 605 a set of one or more emittance models is provided (where theset includes one or more reconstructions of the body structure). Anemittance model specifies the radiative intensity of each voxel in thebody structure. As discussed above, some of the viewing parametersaffect the radiative intensity of the voxels in the volume, for examplethe type of radiopharmaceutical and the time since administration of theradiopharmaceutical. Therefore, the emittance models provided in step605 preferably correspond to the relevant viewing parameters. In step606 a collection of possible further views of the body structure isprovided. The collection of views includes possible further views forfuture measurements, preferably based on anatomical and otherconstraints. Furthermore, the quality function provided in step 610 mayutilize multiple emission models.

In the preferred embodiment, one or more of the emittance modelscontains at least one high-emittance portion (i.e. hot region). Aprostate containing a tumor, for example, may be modeled as an ellipsoidvolume with one or more high-emittance portions.

In the preferred embodiment, one or more of the emittance modelscontains at least one low-emittance portion. A diseased heart maytherefore be modeled as a heart-shaped volume with low-emittanceportions.

Note that an emittance model need not contain high- or low-emittanceportions, but may have a uniform intensity or a slowly varyingintensity.

In a first preferred embodiment the quality function implements aseparability criterion. The implementation and evaluation of theseparability criterion for active view determination is performedsubstantially as is further described herein.

In a second preferred embodiment, the quality function implements areliability criterion. The implementation and evaluation of thereliability criterion for active view determination is performedsubstantially as described herein.

Maximization of the quality function may be performed utilizing anymethod known in the art such as simulated annealing and gradient ascent.In the simulated annealing (SA) method, each point of the search spaceis compared to a state of some physical system. The quality function tobe maximized is interpreted as the internal energy of the system in thatstate. Therefore the goal is to bring the system from an arbitraryinitial state to a state with the minimum possible energy.

The neighbors of each state and the probabilities of making a transitionfrom each step to its neighboring states are specified. At each step,the SA heuristic probabilistically decides between moving the system toa neighboring state s′ or staying put in states. The probabilities arechosen so that the system ultimately tends to move to states of lowerenergy. Typically this step is repeated until the system reaches andacceptable energy level.

Gradient ascent, on the other hand, is based on the observation that ifa real-valued function F(x), such as the quality function of the presentembodiments, is defined and differentiable in a neighborhood of a pointa, then F(x) increases fastest if one goes from a in the direction ofthe gradient of F at a, ∇F(a). It follows that if:b=a+∇F(a)  (19)for γ>0 a small enough number, then F(a)≦F(b). Gradient ascent startswith a guess x₀ for a local maximum of F, and considers the sequence x₀,x₁, x₂, . . . such that:x _(n+1) =x _(n) +γ∇F(x _(n)), b≧0.  (20)

Since F(x₀)≦F(x₁)≦F(x₂)≦ . . . , the sequence (x_(n)) is expectedconverges to a local maximum.

Preferably, the set of views selected with the quality function isincreased by at least one randomly selected view. The randomly selectedview(s) increase the probability that the quality of informationobtained with the further views is maximized globally rather thanlocally.

As discussed above, selecting the best set of size N from amongst alarge set of candidate projections is computationally complex. Since thesize of the collection of views and of the required set may be large, abrute force scheme might not be computationally feasible.

In an additional preferred embodiment, a so-called “greedy algorithm” isused to incrementally construct larger and larger sets, until therequired number of further views is defined. When multiple further viewsare required, it is computationally complex to maximize the qualityfunction over all possible combinations of further views. The greedyalgorithm reduces the computational burden by selecting the furtherviews one at a time. The algorithm starts with a current set of views,and for each iteration determines a single view that yields the maximumimprovement of the set score (hence the name “greedy”).

In theoretical terms, assume p(•) is the quality measure we are usingfor the view selection, and assume without loss of generality that weare trying to maximize this measure. We gradually build a set W ofprojections as follows. We start with an empty set W=Ø, and at everystage choose the projection that maximizes the quality measure whenadded to the current set:W←arg max_(W′){ρ(W′)|W′=W∪{φ},φεΦ}  (21)

In other words, during a given iteration, a respective score iscalculated for a combination of the previous set with each of the viewswhich is not a member of the current set. The current set is thenexpanded by adding the view which yielded the highest respective score,and the expanded current set serves as the input to the followingiteration. Thus the number of times the scoring function is calculatedper iteration drops from iteration to iteration. For a large collectionof possible views, the greedy algorithm reduces the total number ofcomputations required for set selection.

Reference is now made to FIG. 87, which is a simplified flowchart of aniterative “greedy” method for defining further views, according to apreferred embodiment of the present invention. The greedy algorithm isimplemented substantially as described herein. In step 1000 a collectionof views of the body structure is provided. The collection of viewsincludes possible further views for future measurements, preferablybased on anatomical and other constraints. In step 1010, the set ofviews used for the previous emission measurements is established as acurrent set of views. In step 1020 the view set is incrementallyincreased by a single further view during each iteration, until therequired number of further views has been selected.

Reference is now made to FIG. 88, which is a simplified flowchart of asingle iteration of the view selection method of FIG. 87, according to apreferred embodiment of the present invention. The method of FIG. 88expands the current set of views by a single view. The method beginswith a current set of views, which is the predetermined set (step 1010above) for the first iteration of the greedy algorithm, or the setformed at the end of the previous iteration (step 1120 below) for allsubsequent iterations. In step 1100, a respective expanded set is formedfor each view not yet in the current set of views. A given view'sexpanded set contains all the views of the current set of views as wellas the given view. In step 1110, a respective score is calculated foreach of the expanded sets using the quality function. In step 1120, theview which yielded the highest-scoring expanded set is selected as afurther view, to be used for further radioactive emission measurements.Finally, in step 1130, the current set is equated to the highest-scoringexpanded set by adding the selected view to the current set. The newlyformed current set serves as an input to the subsequent iteration, untilthe desired number of views is attained.

Reference is now made to FIG. 89, which is a simplified flowchart of amethod for dynamically defining further views, according to a thirdpreferred embodiment of the present invention. In step 1210, acollection of possible further views for performing radioactive-emissionmeasurements of the body structure are provided. Each of the views isassociated with at least one viewing parameter. Preferably the viewingparameters consist of at least one the following: detector unitlocation, detector unit orientation, collection angle, and measurementduration.

In step 1220 at least one quality function is provided. Each qualityfunction is for evaluating sets of views, essentially as describedabove. A single quality function may be used to select several sets ofviews, where each set of views contains a different number of views.

In step 1230, multiple sets of further views (where a set may include asingle further view) are formed from the collection of views, using thequality function(s) provided in step 1220. In a first preferredembodiment, each of the sets is formed using a different one of thequality functions. In an alternate preferred embodiment, one or more ofthe quality functions are used to form more than one set of views, wheresets formed with the same quality function have differing numbers ofviews.

In step 1240, a selected set of views is obtained from the sets formedin step 1230.

In a first preferred embodiment, the final set of views is obtained bychoosing one of the sets formed in step 1230 using a set selectioncriterion. For example, a respective set is formed in step 1230 for theseparability and reliability criteria independently. A set selectioncriterion which calculates an overall performance rating for a given settaking both criteria into account is defined, and the formed set withthe highest overall rating is selected as the final set.

In another preferred embodiment, the selected set of views is obtainedby merging the sets formed in step 1230 according to the relativeimportance of the respective quality function used to form each set.

In the preferred embodiment, the method further consists of providing atleast one emittance model and/or reconstruction representing theradioactive-emission density distribution of the volume, and ofevaluating with at least one of the quality functions of step 1220 isperformed in relation to the emittance models.

As discussed above, since each view is associated with one or moreparameters, the selected set yields a group of parameter values forperforming effective detection of the intensity distribution of the bodystructure. For example, if each view is associated with a view locationparameter the selected set defines a set of locations for collectingemission data from an object, in order to provide a high-qualityreconstruction of the intensity distribution of the body structure.

Reference is now made to FIG. 90, which is a simplified block diagram ofmeasurement unit for performing radioactive-emission measurements of abody structure, according to a preferred embodiment of the presentinvention. Measurement unit 1300 includes probe 1310, analyzer 1320 andview definer 1330. Probe 1310 performs the radioactive-emissionmeasurements of the body structure. Radioactive-emission-measuring probe1310 preferably comprises several detecting units, which may be ofdifferent geometries and different collection angles δ, within ahousing. Preferably, the orientation and/or collection angle of theindividual collimators is controllable. Analyzer 1320 analyzes theradioactive-emission measurements obtained from probe 1310. View definer1330 dynamically defines further views for measurements, based on theanalysis provided by analysis unit 1320. The analysis and viewdefinition are performed substantially as described above.

The abovedescribed methods for radioactive-emission measurements of abody structure begin by performing measurements at a predetermined setof views. The results of the initial measurements are then analyzed andfurther views are defined.

The initial set of views is preferably selected based on informationtheoretic measures that quantify the quality of the data fed to thereconstruction algorithm, in order to obtain the best data forreconstructing a three-dimensional image of the body structure, asdescribed herein. The following section concentrates on the second stepof the process, namely, obtaining the optimal and permissible set ofinitial views for performing the radioactive-emission measurements ofthe body structure. The initial predetermined set of views is denotedherein the optimal set of views.

The initial predetermined set of views is preferably selected inaccordance with the method of the view selection as described herein.Preferably the initial predetermined set of views is selected on thebasis of one or a combination of the separability, reliability, anduniformity criteria.

The abovedescribed methods may each be embodied as a computer programstored on a computer-readable storage medium. In the preferredembodiment, computer-readable storage medium contains a set ofinstructions for defining views for radioactive-emission measurements ofthe body structure. An analysis routine analyzes theradioactive-emission measurements obtained from aradioactive-emission-measuring probe, and a view definition routinedynamically defines further views for measurements, based on theanalyzing.

By enabling high-quality reconstruction based on data collected from alimited collection of views, the abovedescribed view set selectiontechniques present a way to resolve the current conflict between therelatively large-pixel detectors needed for measurement speed and dataprocessing considerations, with the small-pixel detectors needed untilnow to obtain a high-resolution reconstruction. The data obtained usingthe selected set of views enables a high-resolution reconstruction froma smaller number of measurements. Additionally, reconstructing theintensity distribution from a smaller quantity of collected datasimplifies the computational process. The abovedescribed embodiments areparticularly suitable for medical imaging purposes, where ahigh-resolution image is needed and it is desired to minimize thedifficulties of the patient undergoing the diagnostic testing ortreatment.

Voxel Dynamic Modeling

Dynamic modeling is a technique in which the parameters of a dynamicsystem are represented in mathematical language. Dynamic systems aregenerally represented with difference equations or differentialequations. Measurements obtained from the modeled system can then beused to evaluate the values of parameters of interest that cannot bemeasured directly.

In the present case, the system being modeled is the body structure (orportion thereof) being imaged. During imaging, the emittance from agiven voxel is affected by the chemical properties of theradiopharmaceuticals well as by the half-life of the tracer, as well asby the nature of the body structure being imaged. For example, thechemical properties of the antibody to which the tracer is attachedgovern factors such as binding to the tissue, accumulation, andclearance rate.

The goal of the presented models is to recover the kinetics per voxel ofone or more parameters of interest. Each of the models reflects adifferent mechanism for the diffusion of the radiopharmaceutical intoand out of the voxel, as well as the possibility of accumulation withinthe voxel. For a given measurement process the dynamic model should beselected to match the known properties of the radiopharmaceutical beingused.

Reference is now made to FIG. 91, which is a simplified flowchart of amethod for measuring kinetic parameters of a radiopharmaceutical in abody, according to a preferred embodiment of the present invention. Instep 6010, the radiopharmaceutical is administered to the body. In step6020, the body or a portion of the body are imaged. In step 6030, amodel is provided for obtaining kinetic parameters from the imaging isprovided. Several preferred embodiments of dynamic models are presentedbelow. Finally, in step 6040, the kinetic parameters are obtained byapplying the measurements to the provided model in order to extract thevalue of the required parameter(s). The kinetic parameters may provideinformation on factors such as actual uptake, rate of uptake,accumulation, and clearance of the radiopharmaceutical, which in turnprovide information about the health of tissue in the voxel. Theobtained parameter values can thus be analyzed to evaluate the health ofthe imaged body structure and of other portions of the body (for examplerenal functioning). (See description of expert system) The parametervalues can also be analyzed and used to control future administration ofthe radiopharmaceutical (See description of closed loop injectionsystem). The parameters obtained in step 6040 preferably include atleast one of: local (in-voxel) representation of blood pool, blood flow,and diffusion to and/or from the local tissue as representative offunction (e.g. viability).

Three preferred embodiments of dynamic models for provision in step 6030are now presented. The following rationale and assumptions are common toall of the presented embodiments.

The analysis is of one voxel versus the rest of the body, not of theentire organ.

The dynamic model relates the per pixel emission levels to factors suchas the blood in voxel, the tissue in voxel (and uptake from blood), andblood re-fill (perfusion/flow).

An additional assumption is that the amount of the tracer in the voxelis insignificant compared with the rest of the body and with the globalblood pool. Therefore, the voxel in the region of interest (ROI) isaffected by the global blood pool, but does not affect it. As a result,the concentration of tracer in the global blood pool can be recoveredseparately by one or more of: modeling the known kinetics given theexact injected dose, measuring the concentration at a pre-identifiedblood region using the imaging equipment, or by taking blood samplesover time.

It is also assumed that the concentration of the tracer in the globalblood may be controlled in a complex fashion by various injectionprofiles, such as:

1) Bolus injection

2) Constant drip

3) Smart injection—in which the radiopharmaceutial is injected in acontrolled manner over time. The smart injection profile may bepredetermined, or responsive to external events and/or feedback from theimaging equipment (see closed loop description). For example, ratherthan injecting a single bolus dose of radiopharmaceutical, one caninject a tenth of the dose for each of a series of ten injections.Examples of smart injection profiles are described below.

It is assumed that in ischemic conditions, not enough blood flow reachesthe voxel, thus the concentration of the tracer in the blood of thatvoxel is different than in global blood pool. For example, if oxygen isthe tracer, then ischemic region has lower oxygen concentration in thecapillaries than in global blood pool due to poor refill.

An additional assumption is that the processes affecting the tracerconcentration are slower than fractions a second, so that the volume andflow values (as defined below) relate to an average over the heartcycle. Thus gating will not separate the uptake into the tissue fordifferent time slices in the heartbeat. Gated analysis (which issynchronized with the heart cycle) may be developed for fast processeswhich do not involve slow accumulation in the muscle tissue, or,alternatively, model the accumulation, both of which requires motioncompensation.

A final assumption is that each voxel is large enough so that variablesmay be defined to relate to the voxel structure in global terms. Thedynamic models described below are for voxels having a millimetric size,which are therefore significantly larger than the blood vessels (unlikeduring imaging of blood vessels). The models therefore includeparameters for both blood and tissue parameters. In cases where a veryhigh-resolution reconstruction (i.e. sub-millimetric) is required, adifferent model should be applied to handle voxels which are pure blood(e.g. voxels inside coronaries).

The following parameters are defined for all of the dynamic modelembodiments presented below:

1) Vt—Volume of tissue in voxel.

2) Vb—Volume of blood within the capillaries in the given voxel. Vb isnormally constant for a given tissue type, but may vary for differenttissue types such as blood vessel, connective tissue, or tumor before orafter angiogenesis

3) V—Voxel volume. The voxel volume is the sum of the tissue volume andblood volume within the voxel:V=Vt+Vb  (1)

V is a fixed value dictated by the imaging equipment (i.e. camera)performing the radioactive-emission measurements.

4) Rb—Density of blood within the voxel. Rb is the ratio of the volumeof the blood in the voxel to the total voxel volume:Rb=Vb/V  (2)

For example, in cross section, the diameter of a capillary is about10-15 um. To allow diffusion to cells the capillaries are spaced about50-150 um apart. Therefore, it is reasonable to assume that healthytissue has Rb˜1-5%

5) F—Blood flow to voxel. It is assumed that blood flow is not affectedby neighboring voxels (i.e. blood flow is of “fresh” blood from thearteries).

6) Cb—Tracer concentration in blood within the voxel (reflects thecapillaries in the voxel).

7) Ct—Tracer concentration in tissue within the voxel.

8) C—Tracer concentration in voxel, as measured by the imagingequipment.

9) Cg—Tracer concentration in global blood. The concentration in theglobal blood supply is assumed to be given. C may be determined with aseparate model, or by measuring the global blood concentration directly.A full model of Cg should reflect many of the patient's conditions,including cardiac output, prior diseases (such as metabolic disorders ordiabetes), hyper/hypo-fluid volume, hyper/hypo-blood pressure, liverand/or kidney function, drugs (diuretics), and so forth.

Note that all of the above parameters other than Cg are defined pervoxel.

Reference is now made to FIG. 92, which is a schematic representation ofa dynamic model of a voxel, according to a first preferred embodiment ofthe present invention. The present embodiment (denoted herein model 1)assumes symmetric diffusion (i.e. the tracer diffusion coefficients intoand out of the voxel are equal), and that there is no accumulation ofthe tracer within the voxel. FIG. 92 illustrates the role of each of theparameters described above.

The radioactive pharmaceutical is introduced into the global blood pool6110 by injection according to an injection profile 6120. Theradiopharmaceutical is conveyed to the voxel via the circulatory system6125. The radiopharmaceutical flows through the voxel via thecapillaries 6130 running through the voxel at flow rate F. Diffusionfrom the capillaries 6130 to the voxel tissue 6140 (uptake) and from thevoxel tissue 6140 to the capillaries 6130 (release) occurs with a commondiffusion coefficient Kd. Kd is an effective coefficient which takesinto account both the uptake and outtake diffusion coefficients, and thesurface area to volume ratio of the capillaries 6130. The remainder ofthe pharmaceutical is dispersed to the rest of the body for uptake andclearance 6145.

Similar or identical components are indicated with the same referencenumbers throughout the figures.

Model 1 assumes tracer delivery to the voxel by diffusion to and fromthe local tissue, rather than by accumulation and dissolution.Therefore, model 1 can serve for applications with materials likeThallium and CardioTech, but not with Mibi which accumulates due todifferent diffusion rates in and out of the tissue. Models 2 and 3,which are presented below, allow for accumulation, and are thereforemore suitable for radiopharmaceuticals such as Mibi.

Equations 3-5 present the relationship between the kinetic parametersfor model 1:

$\begin{matrix}\begin{matrix}{C = \frac{{{Ct} \cdot {Vt}} + {{Cb} \cdot {Vb}}}{V}} \\{= {{{Cb} \cdot {Rb}} + {{Ct} \cdot \left( {1 - {Rb}} \right)}}}\end{matrix} & (3) \\{\frac{\mathbb{d}{Ct}}{\mathbb{d}t} = {{Kd}\left( {{Cb} - {Ct}} \right)}} & (4) \\{{\frac{\mathbb{d}{Cb}}{\mathbb{d}t} = {{\frac{F}{Vb}\left( {{Cg} - {Cb}} \right)} - {{Kd}\left( {{Cb} - {Ct}} \right)}}}{{{{Initial}\mspace{14mu}{Conditions}\text{:}\mspace{11mu}{Ct}} = 0},{{Cb} = 0}}} & (5)\end{matrix}$

C is measured dynamically by the imaging equipment and Cg is determinedseparately by measurement or independent modeling from the art.

Reference is now made to FIG. 93, which is a schematic representation ofa dynamic model of a voxel, according to a second preferred embodimentof the present invention. The present embodiment (denoted herein model2) assumes symmetric diffusion, with a diffusion coefficient of Kd. Asin model 1, Kd is an effective coefficient which takes into account boththe uptake and outtake diffusion coefficients, and the surface area tovolume ratio of the capillaries 6130. However, in contrast with model 1,model 2 assumes that a fraction 6150 of the tracer concentration withinthe tissue is accumulated and is not diffused back to blood (for exampleby metabolism). The tracer accumulation within the voxel occurs at arate of A.

Equations 6-9 present the relationship between the kinetic parametersfor model 2:

$\begin{matrix}\begin{matrix}{C = {\frac{{{Ct} \cdot {Vt}} + {{Cb} \cdot {Vb}}}{V} + {Accum}}} \\{= {{{Cb} \cdot {Rb}} + {{Ct} \cdot \left( {1 - {Rb}} \right)} + {Accum}}}\end{matrix} & (6) \\{\frac{\mathbb{d}{Ct}}{\mathbb{d}t} = {{{Kd}\left( {{Cb} - {Ct}} \right)} - {A \cdot {Ct}}}} & (7) \\{\frac{\mathbb{d}{Cb}}{\mathbb{d}t} = {{\frac{F}{Vb}\left( {{Cg} - {Cb}} \right)} - {{Kd}\left( {{Cb} - {Ct}} \right)}}} & (8) \\{{{Accum} = {\int_{0}^{t}{{A \cdot {Ct}}{\mathbb{d}t}}}}{{{{Initial}\mspace{14mu}{conditions}\text{:}\mspace{11mu}{Ct}} = 0},{{Cb} = 0},{{Accum} = 0}}} & (9)\end{matrix}$

Reference is now made to FIG. 94, which is a schematic representation ofa dynamic model of a voxel, according to a third preferred embodiment ofthe present invention. The present embodiment (denoted herein model 3)assumes asymmetric diffusion, with uptake and release occurringaccording to the blood concentration (vs. zero) for uptake, and to thetissue concentration (vs. zero) for release, not according to thedifference in concentrations (blood vs. tissue) as in model 1. Transportto the tissue is modeled by a diffusion coefficient of Kin, dependingonly on the outside concentration of capillary blood. Outgoing transportis modeled by a diffusion coefficient of Kout for outgoing transport,depending only on the internal (tissue) concentration. This way,accumulation is described by a high Kin and a low Kout. Kin and Kout areeffective coefficients, which account for the surface area to volumeratio of capillaries.

Equations 10-12 present the relationship between the kinetic parametersfor model 3:

$\begin{matrix}\begin{matrix}{C = \frac{{{Ct} \cdot {Vt}} + {{Cb} \cdot {Vb}}}{V}} \\{= {{{Cb} \cdot {Rb}} + {{Ct} \cdot \left( {1 - {Rb}} \right)}}}\end{matrix} & (10) \\{\frac{\mathbb{d}{Ct}}{\mathbb{d}t} = {{{Kin} \cdot {Cb}} - {{Kout} \cdot {Ct}}}} & (11) \\{{\frac{\mathbb{d}{Cb}}{\mathbb{d}t} = {{\frac{F}{Vb}\left( {{Cg} - {Cb}} \right)} - {{Kin} \cdot {Cb}} + {{Kout} \cdot {Ct}}}}{{{{Initial}\mspace{14mu}{conditions}\text{:}\mspace{11mu}{Ct}} = 0},{{Cb} = 0}}} & (12)\end{matrix}$

Models 2 and 3 are suitable for use with tracers like Thallium and Mibi,since they do not assume symmetric diffusion to/from the local tissue,but rather allow accumulation.

Regarding the parameters of the abovedescribed dynamic models, it may bepossible to attribute the physiological meaning as follows:

1) F may correspond to perfusion

2) Kd+A may correspond to viability and metabolism (Model 2)

3) Kin may correspond to viability (Model 3)

Referring again to FIG. 92, in step 6040 the kinetic parameters for thevoxel are obtained by applying the measured values to the provided modeland extracting the value of the required parameters. Parameterextraction may be performed utilizing any technique known in the art,such as numerical analysis. Repeated measurements may be made of thegiven voxel, and the parameters calculated with increasing accuracy.

In a preferred embodiment, parameter extraction the dynamic system isprovided in step 6030 as an analogous RLC electronic circuit. An RLCcircuit is an electrical circuit consisting of resistors (R), inductors(L), and capacitors (C), connected in series and/or in parallel. Anyvoltage or current in an RLC circuit can be described by a second-orderdifferential equation. Since all of the abovedescribed models presentthe voxel kinetic parameters as a second order system, the dynamic modelprovided in step 6030 may be described as an arrangement of resistors,capacitors, and inductors.

Voltage analysis of an RLC circuit is based on expressing the voltageover each of the circuit elements as a function of the circuit currentas follows:

$\begin{matrix}{{Resistor}\text{:}\mspace{11mu}{V_{R}(t)}{R \cdot {i(t)}}} & (13) \\{{{Capacitor}\text{:}\mspace{11mu}{V_{C}(t)}} = {\frac{1}{C}{\int_{- \infty}^{t}{{i(\tau)}{\mathbb{d}\tau}}}}} & (14) \\{{{Inductor}\text{:}\mspace{11mu}{V_{L}(t)}} = {L\frac{\mathbb{d}i}{\mathbb{d}t}}} & (15)\end{matrix}$

As an example of RLC circuit analysis, consider the series RLC circuit6160 shown in FIG. 95. RLC circuit 6160 consists of resistor 6165,inductor 6170, and capacitor 6175 connected in series, with an inputvoltage provided by voltage source 6180. In a series RLC circuit, thetotal voltage drop over the circuit is the sum of the voltage drop overeach of the circuit elements, so that:

$\begin{matrix}{{{V(t)} = {{R \cdot {i(t)}} + {L\frac{\mathbb{d}i}{\mathbb{d}t}} + {\frac{1}{C}{\int_{- \infty}^{t}{{i(\tau)}{\mathbb{d}\tau}}}}}}{{and}\text{:}}} & (16) \\{\frac{\mathbb{d}V}{\mathbb{d}t} = {{L\frac{\mathbb{d}^{2}I}{\mathbb{d}t^{2}}} + {R\frac{\mathbb{d}i}{\mathbb{d}t}} + {\frac{1}{C}{i(t)}}}} & (17)\end{matrix}$

Presenting the dynamic model as an RLC circuit enables using well-knowncircuit analysis techniques to derive the values of the desiredparameters based on the measurements, and to analyze the behavior of thedynamic system. In terms of the abovedescribed dynamic modeling, thevoltage, V, represents the administered radiopharmaceutical, and dV/dtrepresents the rate of change of the administered radiopharmaceutical,that is the administration protocol. The circuit function (e.g. theright hand side of equation 17) is analogous to the obtained image.Since the obtained image is dependent on Ø, the probability that aphoton emitted by the given voxel is detected by the imaging equipment,the circuit function is a function of Ø. The RLC analogy can thus beused in order to determine the radiopharmaceutical input function,dV/dt, which optimizes Ø.

Possible forms for dV/dt include bolus injection (V(t) is a single pulseat t=0), constant drip (V(t) is a constant), and smart injectionprofile. Following are non-limiting examples of smart injectionprofiles:

1) Randomly (e.g. in the range of about every 1 to 200 sec)

2) Periodically every T seconds

3) Synchronized to the camera acquisition cycle. For example, if thecamera produces a full volume scan every 5 seconds the injections aresynchronized with each repetition of the scan. Synchronizing with cameraacquisition allows better spatio-temporal coverage, as the injection andthe scanning plans may be optimized together.

4) Synchronized to motion-related events. Motion-related events mayinclude one or more of expiration, inspiration, cardiac movement,stomach contraction, gastro-intestinal movement, joint movement, organmovement, and so forth. For example, motion-synchronized injection maybe used to inject and/or acquire during a relatively stable time periodor a relatively motion-intensive time period.

5) Synchronized to physiological events (which may be acquired byanother system). Physiological events may include a change in theactivity of an organ or tissue (such as O₂/CO₂ concentration), glucoseconcentration, changes in perfusion, electrical activity (ECG, EMG, EEG,etc . . . ), neuronal activity, muscular activity, gland activity, andso forth.

6) Synchronized to an external event, for example to an externalstimulation (e.g. by motion, sound, or light) or drug administration.Synchronizing with a drug administration may be useful for proceduressuch as imaging of cerebral perfusion events (like in functional MRI),so that a small bolus may be injected per stimulus and the region thatuptakes the radiopharmaceutical will be more likely to be related to thestimulus.

7) Responsive to the radiopharmaceutical concentration in the blood. Bymonitoring the level of the radiopharmaceutical in the blood (either bydrawing blood samples or by determining the level with the camera orother measurement system) it is possible to control the pattern in theblood, for example to keep a desired level, a desired slope, cycles, andso forth. In particular, when the frequency domain is used for the finalanalysis it may be beneficial to have the injection profile in one ormore fixed periods (frequencies) selected to fit the expected kineticprofile, and to keep the concentration in the blood controlled so as toproduce a desired spectral performance of the blood concentration, forexample an approximately sinusoidal, saw-tooth, other harmonic form.When the level in the blood is provided by the camera, a closed loopsystem is obtained (see closed loop description).

By synchronized to an event it is meant that the injection timing issubstantially linked to the timing of the event; for example theinjection is performed at the time of the event, at a predetermineddelay after it, or at a predicted time before the event. Suchsynchronization may allow summing and/or averaging the collected data ina synchronized fashion, similar to gating. Such summing/averagingenables the analysis and amplification of information related to thedesired event, while all events which are not synchronized become“blurred”, and have less influence on the final result. For example, aninjection profile of once every two seconds allows data accumulated fora dynamic event synchronized to a two second period to be collected andaveraged. External interferences, such as breathing, heart motion, andsudden patient motion, become less influential as they are notsynchronized with the two second cycle. Therefore the signal to noiseratio and errors in the reconstructed kinetic parameters are reduced.

Reference is now made to FIG. 96, which is a simplified flowchart of amethod for measuring kinetic parameters of a radiopharmaceutical in anorgan of a body, according to a preferred embodiment of the presentinvention. The present method differs from the method of FIG. 91 in thatit images a specific organ of the body. In step 6210, theradiopharmaceutical is administered to the body. In step 6220, the organis imaged. In step 6230, a model is provided for obtaining kineticparameters from the imaging is provided. Finally, in step 6240, thekinetic parameters are obtained by applying the measurements to theprovided model and extracting the value of the required parameter(s).

A further preferred embodiment of the present invention is a drugformulation for a radiopharmaceutical. Reference is now made to FIG. 97,which is a simplified flowchart of a process for obtaining the drugformulation, according to a preferred embodiment of the presentinvention. In step 6310, kinetic parameters for the radiopharmaceuticalare provided. In step 6320, the formulation is determined, based on theprovided kinetic parameters. The values of the kinetic parameters arepreferably obtained by the method of FIG. 91 described above.

In the abovedescribed models C is modeled as a concentration.Alternatively, C may be modeled as a count rate. For eachradiopharmaceutical there is a conversion ratio from concentration tocount rate which depends on several factors. Factors influencing theconversion may include: mg of matter to number of molecules, theradiopharmaceutical half-life (which determines the average time for aphoton to be emitted per molecule), and the rate of isotope decay. Ifthe half-life is short, there is a reduction in available isotopes overthe time of acquisition. Modeling the count rate may therefore beeasier, and allow later conversion to concentrations.

Commonly, the time for a compound to become widespread in the body is inthe time scale of about one minute. Thus the sharp slope inconcentration observed immediately following injection lasts only a fewseconds before various organs begin uptaking the compound. It istherefore preferable to allow scanning and reconstruction of volumes ofinterest in a time resolution of about 5-10 seconds. Since the modelequations include relatively few parameters, it is assumed that withacquisition of a few minutes long (1, 2, 5, 10 minutes) the number oftime points obtained per voxel is in the range of 10-20 (preferably 50or more), which is expected to enable stable estimation of the kineticparameters. With radiopharmaceuticals having slower uptake and releaseactivity it may be preferred to have longer acquisition times, such as20, 30, or 60 minutes.

The analysis and determination of parameter values may be performed inthe time domain, the frequency domain, or in any other transform domain.In the time domain, analysis is performed by solving the differentialequation, either analytically or numerically, in order to reach a modelwhich best fits the acquired data. Various numerical tools are known tofit equations of this complexity to a given data set. An example offrequency domain analysis is presented below.

The analytical solution may include integration over the input Cg, whichmay not be available with sufficient accuracy. In such cases, numericalmethods for fitting the differential equations may prove more stable andaccurate.

It is expected that frequency domain analysis will be particularlyeffective when the data is acquired in a frequency representation. It isexpected that time domain analysis will be particularly effective whenthe data is obtained over time. Alternative approaches may be tested byconverting the data from one form to the other, and the more stableapproach may be selected.

In some cases, the model above may further include interstitial volume,so that substances move from capillaries to the interstitial domain andfrom there to the cells, and vice versa. Transfer to and from theinterstitial domain may be added to the equations. In many cases thedifference in concentration between the interstitial volume and thecapillaries is insignificant, thus they may be modeled as one domain.

It should be noted that the general blood concentration, Cg, may differfrom one location to another, for example between veins and arteries.Therefore, it may be preferable to measure the blood concentration by asample from the arteries or by measuring the concentration inside theleft chambers of the heart.

Similarly, in the case of cardiac imaging there might be poor blood flowalong one or more of the coronary arteries, and thus uptake of substanceby cells in one voxel might reduce the remaining concentration in theartery available for voxels further along the given artery. Thus thevalue of Cg may actually be lower for the more distal voxels. Changes inthe value of Cg may be handled by iterating the parameter estimationwhile correcting the Cg value once the uptake in the more proximalvoxels has been estimated.

Note that if the radiopharmaceutical administration is based on aperiodic injection protocol, the concentration in the general blood pool(either arterial or venous) may respond in a periodic pulsatile profile,which has a harmonic spectrum.

Following is a discussion of the application of frequency domainanalysis to the abovedescribed voxel dynamic modeling. Frequency domainanalysis allows the use of techniques for measuring the frequencyresponse to a periodic injection protocol, similarly to the wayfrequency response is evaluated in passive electrical circuitries. Forexample, the frequency response may be measured by injecting theradiopharmaceutical at several frequencies, and then determining theamplitude of the response at a given frequency, the phase response, orthe comparative amplitudes at several frequencies. The results are thencompared with the model of the frequency response and parameters ofinterest are extracted (e.g. resistors and capacitor values inelectrical circuitry, or diffusion coefficients and blood flow, F, inthe voxel dynamic model).

Taking model 3 as an example, the Fourier transform equivalents ofEquations 10-12 are:

$\begin{matrix}{C = {{\left( {{{Ct}*{Vt}} + {{Cb}*{Vb}}} \right)/V} = {{{Cb}*{Rb}} + {{Ct}*\left( {1 - {Rb}} \right)}}}} & (18) \\{{j\;{wCt}} = {{{Kin} \cdot {Cb}} - {{Kout} \cdot {Ct}}}} & (19) \\{{j\;{wCb}} = {{\frac{F}{Vb}{\left( {{Cg} - {Cb}} \right) \cdot {Kin} \cdot {Cb}}} + {{Kout} \cdot {Ct}}}} & (20)\end{matrix}$

where C, Cb, Ct, Cg are in the frequency domain, w is the angularfrequency, and j is the imaginary unit, √{square root over (−1)}).

Equations 18-20 result in Equation 21, which relates the concentrationin the voxel of interest (C) to the concentration in the arterial blood(Cg) in the frequency domain:

$\begin{matrix}{C = \frac{\frac{F \cdot {Cg}}{V}\left\lbrack {\frac{Vt}{Vb} + \frac{\;{{j\; w} + {Kout}}}{Kin}} \right\rbrack}{{\left( {{j\; w} + \frac{F}{Vb} + {Kin}} \right) \cdot \left( \frac{{j\; w} + {Kout}}{Kin} \right)} - {Kout}}} & (21)\end{matrix}$

The relationship between C and Cg can be measured in severalfrequencies, enabling the extraction of F, Kin, and Kout.

Equation 21 is useful for analyzing the value of the kinetic parameters.Consider the case of w<<Kout, that is the case in which rate ofclearance is much faster than the rates of changes in the blood flow. Inpractice, it is difficult to obtain w<<Kout for someradiopharmaceuticals, requiring slow and controlled changes in the bloodconcentration.

For w<<Kout, Equation 21 becomes:

$\begin{matrix}{\frac{C}{Cg} = {\frac{\frac{F}{V}\left\lbrack {\frac{Vt}{Vb} + \frac{Kout}{Kin}} \right\rbrack}{\left( {{j\; w} + \frac{F}{Vb}} \right) \cdot \left( \frac{Kout}{Kin} \right)} = {\frac{F}{V} \cdot \frac{\frac{{Vt} \cdot {Kin}}{Kout} + {Vb}}{{j\;{wVb}} + F}}}} & (22)\end{matrix}$

Equation 22 provides a highly important relationship, as the ratiobetween two measurements, each with two different low frequencies w1 andw2 (i.e. two slow derivatives of concentration changes), provide adirect measure of flow rate:

$\begin{matrix}{\frac{\left( {C/{Cg}} \right)_{2}}{\left( {C/{Cg}} \right)_{1}} = \frac{{j\;{w_{1} \cdot {Vb}}} + F}{{j\;{w_{2} \cdot {Vb}}} + F}} & (23)\end{matrix}$

The ability to isolate parameters, so that the values of differentparameters do not affect each other, is of high importance. Parameterisolation combined with the high sensitivity and the ability to producemultiple repetitions in different frequencies or slopes may enableextracting some parameters in a quantitative and efficient manner.

Quantification in the case of w<<Kout depends on the prior estimation ofthe partial volume in each voxel containing the blood compartment. OnceF is known, the ratio of Kin/Kout is obtainable from the Equation 22above.

In a more typical scenario, w>>Kout, and equation 21 becomes:

$\begin{matrix}{\frac{C}{Cg} \cong {\frac{F}{V} \cdot \frac{{{Kin} \cdot {Vt}} + {{jw} \cdot {Vb}}}{{jw}\left( {{{jw} \cdot {Vb}} + {{Kin} \cdot {Vb}} + F} \right)}}} & (24)\end{matrix}$

For w>>Kout, measuring the ratio of C/Cg in multiple frequencies allowsthe recovery of the flow F and the wash-in rate Kin (which is associatedwith the well being of the cells) in a quantitative manner.

It is possible to perform all analyses in terms of the absoluteamplitudes of C and Cg by converting the modeling equations (whichinclude complex numbers) to absolute numbers. Alternatively, phaseanalysis may be used. An additional alternative is to transformtime-domain signals into the frequency domain with the Fouriertransform, and to perform the remaining analysis in the frequencydomain.

Closed Loop Injection

The ability to perform analysis of the image while imaging takes placeprovides many avenues for dynamically controlling the measurementprocess, so as to optimize the imaging. The present embodiments addressthe analysis of radioactive-emission measurements obtained during acurrent measurement process in order to control the administration ofthe radiopharmaceutical in real-time.

Controlling the administration of the radiopharmaceutical in real-time(denoted herein closed loop administration) enables the development ofprotocols for continuous administration of the radiopharmaceutical, orof repeated administrations while imaging is taking place. Continuingthe administration of the radiopharmaceutical during testing allows theuse of radiopharmaceuticals with a high clearance rate such asteboroxine, whose rapid clearance from the body has made its use forimaging impractical until now.

Reference is now made to FIG. 98, which is a simplified flowchart of amethod of radiopharmaceutical administration and imaging, according to afirst preferred embodiment of the present invention. The present method(denoted herein the stepwise method) is of a stepwise imaging process,which performs a repetitive process of administration followed byimagining and analysis. In step 10000 a first administration of aradiopharmaceutical to a body is performed, in accordance with a firstadministration protocol. The first administration protocol may require asingle injection of a specified quantity of the radiopharmaceutical. Instep 10010 a first imaging of at least a portion of the body isperformed. In step 10020, the first administration protocol isevaluated, based on the first imaging. The evaluation is preferablybased on the detector photon counts and/or on a reconstruction of thebody structure as described below. In step 10030, a secondadministration protocol is determined, based on the evaluating. If theevaluation indicates that the first administration protocol is correct,the second administration protocol may be identical to the firstadministration protocol. In step 10040, at least one additionaladministration of the radiopharmaceutical to the body is performed, inaccordance with the second administration protocol. In step 10050, atleast one additional imaging is conducted.

Reference is now made to FIG. 99, which is a simplified flowchart of amethod of radiopharmaceutical administration and imaging, according to asecond preferred embodiment of the present invention. The present method(denoted herein the dynamic method) evaluates the measurement data whilethe radioactive-emission measurements are being made, so that theadministration of the radiopharmaceutical is controlled simultaneouslywith the imaging. In step 10110 a radiopharmaceutical is administered toa body, in accordance with an initial administration protocol. In step10120, at least a portion of the body is imaged. In step 10130, awhilst-imaging administration protocol is provided, based on theimaging. The whilst-imaging protocol indicates the manner in which theradiopharmaceutical is to be administered while the imaging is takingplace. The imaging process need not be interrupted in order toadminister additional quantities of the radiopharmaceutical. In step10140, imaging is performed simultaneously with the administration ofthe radiopharmaceutical, in accordance with the whilst-imagingadministration protocol.

In essence, the second administration protocol and the whilst-imagingprotocol form a feedback signal which controls radiopharmaceuticaladministration. In the preferred embodiment, the injection system is acontrollable system, and the second administration protocol orwhilst-imaging protocol (denoted herein the new protocol) is provided byan evaluation and control unit as a control signal for the injectionsystem. For example, the control signal for the stepwise method mayconsist of a series of pulses, with the imaging being performed betweenthe pulses. An example of a control signal for the dynamic method is alinear input, where the dosage is steadily increased until it isdetermined that a desired level has been reached. The injection system,imaging equipment, and evaluation and control unit effectively form aclosed loop system, with the control signal providing feedback to theinjection system. See the dynamic modeling description for additionalexamples of administration protocols.

The determination of the new protocol is preferably based on detectorphoton counts and/or reconstructed images obtained from previousmeasurements, similarly to active view determination see active visiondescription.

In the preferred embodiment, determination of the new protocol is basedall or in part on the unprocessed detector photon counts. For example,during evaluation (step 10020 of FIG. 98) it may be determined that thedetector has saturated. The new protocol would then be to allow theradiopharmaceutical to clear and then to apply a smaller dose.

In the preferred embodiment, determination of the new protocol is basedall or in part on the analysis of one or more reconstructions. Forexample, it may be desired to maintain a steady state. A series ofreconstructions is analyzed dynamically, in order to determine whensteady state is reached. The analysis is preferably based on dynamicmodeling—see dynamic modeling description. Reaching steady state may bedetermined from the dynamic model by evaluating Ct, the tracerconcentration in tissue within the voxel, and adjusting theradiopharmaceutical administration in order to maintain Ct at a desiredlevel.

Closed loop administration opens up many new possibilities forradioactive-emission imaging studies. It is anticipated that techniquesfor controlling closed loop administration will be optimized based onfuture studies of responses to different administration protocols.

ERP System and Smart Syringe

The present invention relates to the management of radiopharmaceuticalsubstances used for body structure imaging. More particularly, thepresent invention relates to a system and method for managing theradiopharmaceutical handling processes and the actual imaging processesin a unified manner, so that the managed processes work together in acoordinated manner.

In the business environment, Enterprise Resource Planning (ERP) systemsare information management systems that integrate and automate many ofthe business practices associated with the operations or productionaspects of a company into a single system. ERP systems are customarilyused by large organizations to provide a single system that can managethe manufacturing, logistics, distribution, inventory, and otherbusiness processes across departments in the enterprise. ERP systemsgenerally have a modular structure, with each module handling adifferent aspect of the business processes. The modules are designed towork together, generally using a common database, so as to coordinateall the business processes to work seamlessly together.

The preferred embodiments described below extend the ERP concept byproviding a management system which not only supervises the processesinvolved in ensuring that the radiopharmaceutical is available for theimaging process, but also actively supervises the imaging procedure inorder to ensure that the proper substance is administered to the correctindividual and in the correct quantity.

Reference is now made to FIG. 100, which is a simplified block diagramof a radiopharmaceutical management system, according to a preferredembodiment of the present invention. Management system 9700 includesradiopharmaceutical handling module 9710 and imaging module 9720, bothof which preferably utilize a common database 9730. Radiopharmaceuticalhandling module 9730 coordinates all processes which relate toradiopharmaceutical handling prior to the imaging process, preferablyincluding one or more of: procurement (from outside supplier or bygenerating in-house), inventory (storage), dose preparation, disposal,reporting, and any additional processes required to ensure that arequired radiopharmaceutical is available for the imaging procedure.Some processes may be specific to a particular radiopharmaceutical.Imaging module 9720 coordinates all processes relating to the actualimaging process, preferably including one or more of: patient admission,radiopharmaceutical administration, communication with camera and/oradministration device, and any additional processes required forperforming the imaging. In a further preferred embodiment, describedbelow, the radiopharmaceutical is administered by aremotely-controllable administration device with communicationcapabilities, as described below. Proper design of management system9700 will ensure that adequate safety procedures are in place at alltimes.

Reference is now made to FIG. 101, which is a simplified block diagramof an exemplary embodiment of a radiopharmaceutical handling module.Radiopharmaceutical handling module 9710 has a modular structure. Acentral component of radiopharmaceutical handling module 9710 isinventory module 9730. Inventory module 9730 tracks the types andquantities of the radiopharmaceuticals currently in storage.

Inventory module 9730 is responsible for ensuring that all necessaryradiopharmaceuticals are available. When inventory module 9730identifies that stocks of a given radiopharmaceutical are lower thanneeded, inventory module 9730 notifies procurement module 9740 thatadditional quantities should be procured. Procurement module 9740obtains the necessary radiopharmaceutical, via order module 9741 and/orvia generating module 9742. Order module 9741 places orders withexternal suppliers and tracks delivery. Generating module 9742 managesthe generation of those radiopharmaceuticals which can be generated inhouse (such as Technicium 99m).

When it is necessary to dispose of radiopharmaceuticals, inventorymodule 9730 coordinates with disposal module 9750, which manages thedisposal process.

Both procurement module 9740 and disposal module 9750 operate inaccordance with the per country requirements for radiopharmaceuticaluse. Reporting module 9760 reports to the nuclear regulatory commissionas required, based on information obtained from procurement, disposal,and other modules.

Dose preparation module 9770 manages all tasks related to thepreparation of the radiopharmaceutical doses as required. For a givenimaging procedure, dose preparation module 9770 preferably providesinstructions to a dose preparation system (see FIG. 106) for preparingthe necessary dose, preferably including calculating the required dosageto be dispensed based on factors such as the type of imaging procedure,time of dose preparation, scheduled imaging time, and patient relatedfactors such as age, weight, medical condition and so forth. Dosepreparation module 9770 tracks the number of patient doses drawn fromthe inventory (e.g. mother vial) and updates inventory module 9730accordingly. Additionally, dose preparation module 9770 issues amachine-readable radiopharmaceutical label to be attached to the dose,identifying the radiopharmaceutical type, isotope type, preparation dateand time, time dose should be administered, intended patient, and theintended imaging procedure. The radiopharmaceutical label may consist ofany means of attaching the required information to a given dose, such asa printed label or bar code. In the preferred embodiment describedbelow, the radiopharmaceutical label includes a memory and wirelesscommunication device (in such case the radiopharmaceutical label isdenoted herein a smart label or RFID), to enable direct communicationand information transfer between dose preparation module 9770 and themanagement system. By dose it is intended to include both a singleradiopharmaceutical and a cocktail of radiopharmaceuticals, as requiredby the imaging procedure.

Reference is now made to FIG. 102, which is a block diagram of anexemplary embodiment of an imaging module. Admission module 9810supervises patient admission. At the time of patient arrival, patientdetails such as name, ID number, purpose of visit (type of study), andmedical history are entered, and a patient file is created. Admissionmodule 9810 then generates the patient tag, which is a machine-readabletag to be worn or carried by the patient, and which contains relevantpatient details such as the patient details, intendedradiopharmaceutical dose, and intended imaging scheme. In the preferredembodiment the patient tag is a smart tag 9830 which includes atransceiver, memory, and optionally indicator as described below. Thepatient tag may be in the form of a bracelet or necklace, andAdditionally or alternately, the details may be recorded as text or abar code. Admission module 9810 also notifies ERP module 9820 that thepatient has been admitted, and provides the patient file, includingdetails of the intended study, to ERP module 9820.

ERP module 9820 manages all aspects of the imaging process, bycoordinating between admission module 9820, patient tag, smart label9840, camera 9850, and administration device 9860, in concert withradiopharmaceutical handling module 9710. ERP module 9820 orders andobtains the required radiopharmaceutical dose from dose preparationmodule 9770. The dose is supplied with a smart label 9840. ERP module9820 determines when imaging can begin by comparing data obtained fromsmart tag 9830 (dose), smart label 9840 (patient), and camera 9850,During imaging, ERP module 9820 activates camera 9850 and controls doseadministration by administration device 9860. Preferably communicationbetween the various modules is wireless, according to wireless protocolssuch as Bluetooth, WiFi, W-LAN, and IEEE 802.11.

Camera 9850 includes a controller, communication element (such as atransceiver) for communicating with ERP module 9820, a memory, and anindicator controller, and optionally locking mechanism. Camera 9850 ispreferably activated by ERP module 9820, when ERP module 9820 determinesthat the imaging process may be initiated. The interlock prevents cameraactivation, if the imaging study has not been verified by ERP module9820. ERP module 9820 then controls the camera 9850 in accordance withthe requirements of the current imaging study. For example, ERP module9820 may instruct the camera 9850 to sequentially perform emissionmeasurements at a specified set of views. When imaging is initiated, alight or beep may be provided by the indicator, to notify imagingpersonnel that imaging is about to begin.

Administration device 9860 includes a memory and communication element(such as a transceiver) for communicating with ERP module 9820, andpossibly other system components. Administration device 9860 may be anydevice used to administer a radiopharmaceutical, including a manualsyringe, a controllable-syringe, an IV drip, a pump, or a closed-loopadministration system (see closed loop description). Controllableembodiments of administration device 9860, such as those of FIGS.103-105, include components (such as a motor) for automaticallyadministering and regulating the dose to the patient according toinstructions provided by ERP module 9820. Administration device 9860 maybe preprogrammed with the required administration profile or may beunder online control. In a preferred embodiment, administration device9860 is responsive to responsive to external events and/or feedback fromthe imaging equipment such as those of the smart injection profile (seedynamic modeling description). Administration device 9860 may alsoinclude an indicator, similar to that of camera 9850. Administrationdevice 9860 may be a bedside unit or a portable unit which can becarried by the patient.

Following are exemplary embodiments of the control of the imagingprocedure by ERP module 9820. Prior to administration, ERP module 9820obtains the required dose with a smart label 9840, and sends the dose tothe injection point. In a first preferred embodiment, theradiopharmaceutical is administered by injection prior to imaging, forexample a day early. At the time of administration, ERP module 9820prepares or updates the patient's tag, with the details of the type anddose of radiopharmaceutical that was administered, and preferably thepatient file opened at admission. The following day, at the scheduledtime, the patient arrives at the injection point with the smart tag9830. At the injection point, ERP module 9820 performs a recognitiontest. If there is correlation between the smart label 9840 on thesupplied dose and the patient smart tag 9830, ERP module 9820 determinesthat imaging may commence. Alternately or additionally, ERP module 9820may require manual authorization to begin the imaging process, possiblyby requiring that a personnel member press “START” button on acomputerized camera control screen. ERP module 9820 may additionallyreview medical test results, such as an ECG, for the given patient, toensure that the test results permit performing the imaging.Administration is performable only after ERP module 9820 has unlockedany interlock mechanism or controllable valve on the administrationdevice 9860. Additionally, an indication may be provided by indicatorson the smart tag 9830, administration device 9860 and/or camera 9850.The recognition test ensures that the correct dose is administered tothe patient. Any mismatch between the patient, the radiopharmaceutical,and the intended imaging study prevents radiopharmaceutical from beingadministered.

When dynamic studies are performed it is highly important to image thetime period immediately following administration, when the recentlyadministered radiopharmaceutical causes a rising concentration of theradiopharmaceutical in the blood and in the tissue. Therefore, afterrecognition ERP module 9820 first activates the camera 9850, andauthorizes radiopharmaceutical administration only after the camera 9850is ready. Administration may be performed manually, by preprogramming,or under the control of ERP module 9820 when a controllable syringe (orother administration device) is used. Upon injection a report is sent toERP module 9820, and at least the patient tag, or both the patient's tagand the ERP, are updated that injection took place.

In a second preferred embodiment, the radiopharmaceutical isadministered at the time of the imaging study. When the patient arrives,ERP module 9820 first performs recognition, to ensure a match betweenthe scheduled study, imaging protocol, patient's smart tag 9830, andsyringe smart label 9840. Next ERP module 9820 activates the camera9850. When the camera 9850 has begun imaging, ERP module 9820 initiatesadministration by the administration device 9860, according to either apredetermined administration protocol or to a protocol provideddynamically during the imaging process, possibly via feedback from thecamera (i.e. closed loop).

Reference is now made to FIGS. 103 and 104, which are simplifiedillustrative diagrams of controllable radiopharmaceutical administrationdevices, according to a first and second preferred embodiment of thepresent invention. In the first preferred embodiment, shown in FIG. 103,the administration device is a single-reservoir controllable syringe9861. Controllable syringe 9861 consists of a reservoir 9862, with aninjection volume between about 0.5 to 30 milliliters, surrounded byprotective shielding 9863. Smart label 9864 is attached to theshielding, and is communication with transceiver 9865. Transceiver 9865additionally communicates with the ERP module, for example duringrecognition and while obtaining administration protocol instructions.Transceiver 9865 conveys the administration protocol instructions tocontroller 9866. Controller 9866 controls motor 9867 in order to injectthe pharmaceutical and unlocks controllable valve 9868 (also denoted theinterlock) on needle 9869. Flow rate gate 9870 monitors the dose as itis administered, and provides information about the actual administereddose to one or more of the smart label, smart tag, camera, ERP moduleand controller 9866. Controllable syringe is preferably able toadminister various injection profiles, such as bolus, pulsatile,sinusoidal, or closed loop. Labeling information is optionallyadditionally provided on the syringe as a barcode 9871 or printed label.Controllable syringe 9861 optionally further includes indicator 9872,for providing a visual or audible indication that theradiopharmaceutical is being administered.

In a second preferred embodiment, shown in FIG. 104, the administrationdevice is a multiple-reservoir controllable syringe 9880.Multiple-reservoir controllable syringe 9880 contains multiplereservoirs 9881.1-9881.n for the separate storage of differentradiopharmaceuticals. (FIG. 104 shows a non-limiting example where n=2.)Multiple-reservoir controllable syringe 9880 further contains amechanism for separately controlling administration by each ofreservoirs 9881.1-9881.n. The control mechanism shown in FIG. 104 is aslide 9882 under the control of controller 9866, which preventsadministration from all reservoirs other than the one called for by theadministration protocol.

In the preferred embodiment, a trigger signal is provided by the syringeto the ERP module, indicating that the injection has started and markingthe time point in the patient file. Preferably a trigger is additionallyprovided to mark the end of injection, thereby indicating the durationof administration. In the case of multiple injections, a trigger may beprovided to indicate the start and/or finish of each of theadministrations. The trigger indicating that administration has startedmay be obtained by noting when communication is interrupted between theERP module and a transmitter placed on the plunger portion of thesyringe, as the transmitter signal is blocked by the shielding aroundthe reservoir.

Reference is now made to FIG. 105, which illustrates an administrationdevice for controlled injection of multiple substances into a patientunder the supervision of an imaging module, according to a preferredembodiment of the present invention. The administration device 9910comprises a controller 9912 which receives data from a program and usesthe data to operate a series of syringes 9914 each provided with adifferent tracer or cocktail of tracers. Each syringe contains asubstance which needs to be injected at a certain dose at a certaintime. A valve unit 9916 comprises one or more controllable orone-directional valves which can be used to regulate the amount ofsubstance that reaches the patient or prevent mixing. One valve isprovided per syringe. In essence, administration device 9910 is similarto a parallel battery of single-reservoir syringes all controlled by acentral controller.

The dosage can be controlled by controlling the valves. Control can beprovided based on measuring of the uptake of the radiopharmaceuticals bythe body and/or based on data from flow meters situated respectively oneach one of the valves. Measurement and control can also be carried outvia the syringes themselves, by controlling the plunger.

Uptake and clearance of the radiopharmaceuticals may be monitored bymeasurements of physiological reference points such as blood, saliva,and secretion systems, such as urine, breath, fecal, sweat. Thesemeasurements can serve to estimate pharmacokinetics of theradiopharmaceuticals in the body organs, and to predict optimal imagingtiming. This can be achieved by commonly used devices and kits, or byimaging. Imaging can tell if enough of the substance has for examplereached the liver. Imaging preferably uses a controllable camera underthe control of a management system, however it can use a standard cameraor other stand-alone imaging device.

Based on these estimates, it is also possible to determine expectedlevel of uptake of the radiopharmaceuticals in the target organ, andthus determine pathologies based on absolute uptake levels in the targetorgans.

Dynamic measurements are important in PET. Materials involved in PET,which produce photons, have relatively short lifetimes and the generaltrend is to use extra large doses just to overcome the difficulty of theshort lifetime.

Use of administration device 9910 allows for injection during the timeof imaging, thereby permitting dynamic evaluations, for example imagingand measurement of blood flow, and imaging of blood vessels, includingboth major blood vessels and ranging down to the smallest capillaries.Furthermore the system may permit synchronized imaging of differentsystems, thus imaging of a kind that shows up blood flow which issynchronized with a different imaging operation for bone, so that thetwo can be matched up.

The administration device of FIG. 105 may be shielded to preventradioactive contamination of the environment.

Reference is now made to FIG. 106, which is a simplified block diagramof a dose preparation system 9920, according to a preferred embodimentof the present invention. Dose preparation system 9920 is preferablycontrolled by dose preparation module 9770 of the management system.Dose preparation system 9920 comprises a controller 9922 which receivesas input the identity of the patient for whom the present preparation isbeing made, the patient history, especially pertinent information suchas age, weight, sensitivities, morbidity etc, and the imaging procedurethat the doctor desires to carry out. The imaging procedure may be adetailed procedure or simply indicate the imaging that it is desired tocarry out. The controller 9922 designs a cocktail of substances or aseries of substances to carry out the desired imaging, and usesconstraints from the physical properties of the substances, from thepatient history and from other sources such as safety and efficacyrequirements. The controller 9922 is able to determine what constitutesan appropriate dose for a patient of the given weight and age, and isable to determine at what times different substances should beadministered to the patient in order to achieve optimal imaging. Thuscertain of the isotopes may be administered together and need to becombined in a single preparation. In other cases certain isotopes mayneed to be taken at different times and thus need to be prepared andpackaged separately.

The controller 9922 may be connected to a combiner 9924 which mixes asingle carrier substance with a single isotope, possibly drawn from amother vial. The controller 9922 preferably informs the inventory moduleof the quantities of substances which have been used to prepare thedose. The mixture is passed to first quality control unit 9926 where itis checked for safety and efficacy.

The checked substance is then passed to mixer 9928. In mixer 9928 itwaits for the next carrier isotope combination. All required carrierisotope combinations are collected and mixed in mixer 9928 into a singlepreparation, which is then passed through second quality control unit9930 where it is tested for safety and efficacy.

A labeler unit 9932 produces a label indicating the patient ID, theimaging program, timing information, and other information as describedabove, and the label and mixture are combined into vial 9934. The labelmay be a smart label or a radio frequency identifier (RFID) or a barcodeor a printed label as convenient. The RFID may also be usable foridentifying the patient.

The same patient may be provided with a series of vials, each forinjection at a different time. Each vial may contain one or moreisotopes as appropriate. The vials are inserted into the syringes ofFIG. 104.

In more detail FIG. 106 shows a dose preparation system for providing amixture of carrier substances, tracers and isotopes in a manner suitableto fit a prescribed diagnosis, customized per patient. The system andprocesses include the evaluation, verification, customization, andcombination of the radiopharmaceuticals used in nuclear imaging. In anexemplary embodiment of the invention, the system produces a cocktail ofdifferent radiopharmaceuticals, at various dosages, that is customizedto one or more specific patient injections.

In a first preferred embodiment, control functions are provided by thedose preparation module of the management system. In as second preferredembodiment, controller 9922 of dose preparation system 9920 controlsdose preparation, and updates the dose preparation module. In the secondembodiment, controller 9922 receives data concerning a specific patientundergoing an imaging procedure. Data includes:

-   -   Patient ID    -   Prescription from the physician (which imaging procedure is        required, of what organ, what are the suspected pathologies)    -   Patient parameters such as age, weight, BMI and gender    -   Preferred administration (IV, oral, ventilation,)    -   Patient sensitivity to one or more chemical compounds    -   History of recent radiopharmaceuticals administrations to the        patient (antibodies, isotopes residuals, etc)    -   Physiological tests, e.g. blood, saliva, and secretion systems,        such as urine, breath, fecal, sweat    -   Information concerning patient morbidities such as metabolic        disorders (i.e. diabetes), GI complications and heart disease,        claustrophobia, and other mental disorders    -   Physiological information concerning functioning and/or        complications in liver, spleen, intestines and kidneys

Controller 9922 processes the information and customizes theradiopharmaceutical cocktail according to patient specifications. Thetime for radiopharmaceutical pick up and removal, as well as optimaltiming for injection-to-measurement delta, is all customized. Thisinformation is provided for multiple injections in series or in parallelas well.

The system includes a verification unit that performs quality controlchecks on the raw materials such as the tracer and isotope kits. Forexample, the unit verifies that a specific tracer isotope meetsmanufacturer purity standards, required activity levels andidentification requirements.

The system may include combiner 9924 that combines an individual carriersubstance or tracer to a specific radioisotope.

The system may include mixing unit 9928 that combines and storesmultiple radiopharmaceuticals that have already undergone an initialverification process in first quality control unit 9926.

The system preferably has a radiopharmaceutical cocktail verificationand identification unit, or labeling unit 9932 that, in combination withsecond quality control unit 9930, verifies the presence of the correctsubstances, at the correct dosages. The labeling unit 9932 provides abar code or chip for the patient and the vial 9934 and containsinformation concerning the prescription, dose preparation, timing,injection(s), gamma camera calibration, and analysis of results. Allthis information is linked to the patient smart tag.

The data stored on the smart tag can be read or retrieved in variouslocations:

In an exemplary embodiment of the invention the smart tag(RFID/chip/barcode) is read by the administration device and camera,which is in communication with and under the control of the MRP module.

Low Dose Radiopharmaceuticals

The present invention relates to diagnostic nuclear medicine and, moreparticularly, to packaged dose units of diagnostic radiopharmaceuticalskits and to methods of using same in nuclear imaging.

Diagnostic nuclear medicine began more than 50 years ago and has evolvedinto a major medical branch. Its practitioners use low activity levelsof radioactive materials in a safe way to gain information about healthand disease by administering small amounts of radioactive materials,known as diagnostic radiopharmaceuticals, into the body by injection,swallowing, or inhalation. Following uptake of the radioactive source, aradiation-emission collecting probe, which may be configured forextracorporeal or intracorporeal use, is employed for locating theposition of the active area.

Nuclear imaging is one of the most important tools of diagnosticmedicine wherein an estimated 12-14 million nuclear medicine proceduresare performed each year in the United States alone. Diagnostic nuclearimaging is therefore crucial for studies which determine the cause of amedical problem based on organ function, in contrast to radiographicstudies, which determine the presence of disease based on staticstructural appearance.

Diagnostic radiopharmaceuticals and radiotracers are often designed orselected capable of selective binding to specific receptors by means ofa binding moiety, such as an antibody, a specific inhibitor or othertarget-specific ligand. These targeted markers can therefore concentratemore rapidly in areas of interest, such as inflamed tissues, tumors,malfunctioning organs or an organ undergoing heightened expression ofcertain proteins. Thus, a blood circulating radiopharmaceutical ispicked up by a specific organ or pathological tissue to a differentextent than by other or non-pathological tissue. For example, a highlyvascularized tissue (e.g., of a growing tumor) may concentrate more of aradiopharmaceutical while an ischemic tissue may concentrate less of theradiopharmaceutical than the surrounding tissues. Nuclear imaging relieson these general phenomena of varied distribution of radiopharmaceuticalaccording to different tissue as well as different pathologies. As aresult, specific tissue types (e.g., tumor tissues) may be distinguishedfrom other tissues in radioactive-emission imaging.

Radiopharmaceuticals, which may be used in the process of differentialdiagnosis of pathologies may be conjugated to targeting (recognitionbinding) moieties and include a wide range of radioisotopes as mentionedbelow. Such radiopharmaceuticals therefore include recognition moietiessuch as, for example, monoclonal antibodies (which bind to a highlyspecific pre-determined target), fibrinogen (which is converted intofibrin during blood clotting), glucose and other chemical moieties andagents. Commonly used diagnostic conjugated radiopharmaceuticalsinclude, for example, 2-[¹⁸F]fluoro-2-deoxy-D-glucose (¹⁸FDG),¹¹¹In-Pentetreotide ([¹¹¹In-DTPA-D-Phe¹]-octreotide),L-3-[¹²³I]-Iodo-α-methyl-tyrosine (IMT),O-(2-[¹⁸F]fluoroethyl)-L-tyrosine (L-[¹⁸F]FET), ¹¹¹In-Capromab Pendetide(CYT-356, Prostascint) and ¹¹¹In-Satumomab Pendetide (Oncoscint).

Two basic techniques are widely used for nuclear imaging: positronemission tomography (PET) and single photon emission computed tomography(SPECT). PET detects photons generated through positron-electronannihilation of positrons from a diagnostic radiopharmaceutical tracerplaced in the subject, e.g., patient, to be imaged, and analyzes thephoton energy and trajectory to generate tomographic images of thepatient. SPECT generates images by computer analysis of photon emissionevents from a diagnostic radiopharmaceutical tracer having gammaemitting isotopes. Both PET and SPECT require the detection and analysisof single photon events, which are characterized by low signal to noiseratio and scarcity relative to the background radiation. Otherconstraints on the PET and SPECT image qualities include thesensitivity, temporal and spatial resolution, dynamic range, responsetime and counting rate characteristics of the data acquisition probedevices, e.g., photomultipliers and the like.

Radioisotopes that emit both high energy gamma and/or low energy gamma,beta and/or positron radiation and which can be used per se or as a partof a compound as radiopharmaceuticals, include, without limitation,technetium-99m (^(99m)Tc), gallium-67 (⁶⁷Ga), thallium-201 (²⁰¹Tl),indium-111 (¹¹¹In), iodine-123 (¹²³I), iodine-125 (¹²⁵I), iodine-131(¹³¹I), xenon-133 (¹³³Xe), and fluorine-18 (¹⁸F). All these isotopes,except ^(99m)Tc, ¹³¹I, and ¹³³Xe, are produced in particle accelerators.

The main limitation associated with diagnostic nuclear imaging is therisk associated with humans coming in contact with radioactivematerials. In 1901, five years after discovering radioactivity, HenriBecquerel recognized the risks involved in exposure to radioactiveisotopes. A short time after he had carried a sample of uranium in hispocket, he observed that the underlying skin developed first erythema(reddening of the skin) and then tissue necrosis, which he attributed tothe radioactive properties of the specimen.

Ionizing radiation sources can produce pathological damage by directcell damage or by producing free radicals which are formed throughionization or excitation reactions and which destruct the chemicalintegrity of biological molecules such as DNA and proteins, leading tocell death and cancer. Radiation damage to DNA is due primarily toindirect action of radicals, which leads to the lethal and mutageniceffects attributed to ionizing radiation. On the other hand, the sameeffect is harnessed therapeutically as more rapidly dividing cells aremore sensitive to ionizing radiation.

Other than being a source of ionizing radiation, most radioisotopes andradiopharmaceuticals such as heavy metals, and some targeting(recognition binding) moieties of radiotracers are chemically and/ormetabolically toxic, and can disrupt enzymatic reactions and othermetabolic processes in the body.

The current conservative hypothesis assumes that some risk is associatedwith even the smallest doses of radiation. Furthermore, it is long knownthat while there are safety guidelines for exposure to ionizingradiation such as radioactivity, any dose is harmful because radiativedamage is cumulative over the life span. Today, after more than acentury of careful review of the evidence for radiation effects from theradiation doses associated with diagnostic nuclear medicine, thereappears to be little reason for apprehension about either genetic orsomatic effects (including thyroid cancer) if exposure is controlled,monitored and utterly minimized. Most practitioners and regulationagencies base their dosage regimes on the Nuclear Regulation Committee(NRC) guidelines and follow NRC regulations.

In order to reduce the harmful effects of radiopharmaceuticals andradiotracers, medical use of these chemicals is closely monitored andcontrolled by the NRC which has issued strict guidelines for themanufacture, storage and administered doses of such substances (Siegel,J. A., Guide for Diagnostic Nuclear Medicine, 2002, U.S. NuclearRegulatory Commission).

Diagnostic dose guidelines are set according to the effect of theradiopharmaceutical on body tissue. One parameter which is useful insetting dose limits of diagnostic radiopharmaceuticals is the effectivedose equivalence (EDE) which can be expressed as Roentgen Equivalent Man(rem, the amount of ionizing radiation required to produce the samebiological effect as one rad of high-penetration x-rays) or Sievert (Sv)units, as this unit is defined hereinbelow, wherein 1 rem equals 0.01Sv.

Following are the acceptable definitions of the units serving to measureradiation doses and effective dose equivalents (EDE, described supra).

The Sievert (symbol Sv) or millisievert (mSv) is an SI (InternationalStandards and Units Organization) derived unit of equivalent dose oreffective dose of radiation, and so is dependent upon the biologicaleffects of radiation as opposed to the physical aspects, which arecharacterized by the absorbed dose, measured in grays (see, definitionbelow). The millisievert (mSv) is commonly used to measure the effectivedose in diagnostic medical procedures, e.g., X-rays, nuclear medicine,positron emission tomography (PET) and computed tomography (CT). Forexample, the natural background effective dose rate varies considerablyfrom place to place, but typically is around 3.5 mSv/year. For a fullbody equivalent dose, 1 Sv causes slight blood changes, 2-5 Sv causesnausea, hair loss and hemorrhage, and will cause death in many cases.More than 3-6 Sv will lead to death in less than two months in more than80% of cases.

The Becquerel (symbol Bq) is the SI derived unit of radioactivity,defined as the activity of a quantity of radioactive material in whichone nucleus decays per second. It is therefore equivalent to second⁻¹.The older unit of radioactivity was the curie (Ci), defined as 3.7×10¹⁰becquerels or 37 GBq. It was named after Henri Becquerel, who shared aNobel Prize with Marie Curie for their work in discoveringradioactivity. In a fixed mass of radioactive material, the number ofbecquerels changes with time. In some circumstances, amounts ofradioactive material are given after adjustment for some period of time.For example, one might quote a ten-day adjusted figure, that is, theamount of radioactivity that will still be present after ten days. Thisdeemphasizes short-lived isotopes.

The curie (symbol Ci) or millicurie (mCi) is a former unit ofradioactivity, defined as 3.7×10¹⁰ decays per second. This is roughlythe activity of 1 gram of the radium isotope ²²⁶Ra, a substance studiedby the pioneers of radiology, Marie and Pierre Curie. The Ci has beenreplaced by Bq. One Bq=2.7027×10⁻¹¹ Ci

The gray (symbol Gy) or milligray (mGy) is the SI unit of energy for theabsorbed dose of radiation. One gray is the absorption of one joule ofradiation energy by one kilogram of matter. The gray replaced the rad,which was not coherent with the SI system. One Gy equals 100 rads.

Rem (symbol rem) is the amount of ionizing radiation required to producethe same biological effect as one rad of high-penetration x-rays.

Radiation absorbed dose (symbol rad) is a unit of radiation dose or theamount of radiation absorbed per unit mass of material. Rad wassuperseded in the SI by the Gy. The United States is the only country tostill use the rad. Rads are often converted to units of rem bymultiplication with quality factors to account for biological damageproduced by different forms of radiation. The quality factor for X-raysis 1, so rads and rems are equivalent.

EDE (effective dose equivalence) takes into account the type ofradiation, half life and distribution of an isotope to derive a numberwhich represents the effect on human tissues for milliCurie (mCi, asthis unit is defined hereinbelow) of the isotope administered.

For example, brain perfusion SPECT imaging performed by administrationof a 20 mCi dose of ^(99m)Tc is equivalent to 0.7 rem. This EDE value issimilar to that received during a radionuclide bone scan, is 1.5 timesthat received from a CT of the abdomen and the pelvis, and is 43% of theannual average background radiation in the United States.

When administered to a 70 kg adult male, the average EDE of such dosesfalls within a range of 0.5 to 1.5 rem. Table 2 below presents typicaldoses from several commonly practiced nuclear medicine exams and scansbased on a 70 kg individual, and provide information on prior artdiagnostic radiopharmaceutical doses utilized to carry out these scans.

TABLE 2 Effective Nuclear Radio- Activity Dose Medical Scanpharmaceutical mCi (mBq) mrem (mSv) Brain ^(99m+)Tc 20 (740) 650 (6.5)DTPA Brain ¹⁵O water 50 (1,850) 170 (1.7) Brain ^(99m)Tc 20 (740) 690(6.9) HMPAO Hepatobiliary ^(99m)Tc SCO 5 (185) 370 (3.7) Bone ^(99m)TcMDP 20 (740) 440 (4.4) Lung ^(99m)Tc MAA 5 & 10 (185 & 370) 150 (1.5)Perfusion/ & ¹³³Xe Ventilation Kidney ^(99m)Tc DTPA 20 (740) 310 (3.1)Kidney ^(99m)Tc MAG3 20 (740) 520 (5.2) Tumor ⁶⁷Ga 3 (110) 1,220 (12.2)Heart ^(99m)Tc sestimibi 30 (1,100) 890 (8.9) ^(99m)Tc 30 (1,100) 1,440(14.4) pertechnetate Heart ²⁰¹Tl chloride 2 (74) 1,700 (17) ^(99m)Tc 30(1,100) 845 (8.45) tetrofosmi Various ¹⁸F FDG 10 (370) 700 (7.0)

The regulations for use of radiopharmaceuticals changes in cases ofpatients with lower mass, such as fetuses, infants and children. If apregnant patient undergoes a diagnostic nuclear medicine procedure, theembryo/fetus will be exposed to radiation. Typical embryo/fetusradiation doses for more than 80 radiopharmaceuticals have beendetermined by Russell et al. (Health Phys., 1997, 73: 756-769). For themost common diagnostic procedures in nuclear medicine, the doses rangefrom 0.5×10⁻⁴ to 3.8 rad, the highest doses being for ⁶⁷Ga. Mostprocedures result in a dose that is a factor of 10 or more lower thanthe 3.8 rad dose.

In situations involving the administration of radiopharmaceuticals towomen who are lactating, the breastfeeding infant or child will beexposed to radiation through intake of radioactivity in the milk, aswell as external exposure from close proximity to the mother. Radiationdoses from the activity ingested by the infant have been estimated forthe most common radiopharmaceuticals used in diagnostic nuclear medicineby Stabin and Breitz (J. Nucl. Med., 2000, 41:862-873). In most cases,no interruption in breast feeding is needed to maintain a radiation doseto the infant well below 100 mrem (1 mSv). Only brief interruption(hours to days) of breast feeding was advised for^(99m)Tc-macroaggregated albumin, ^(99m)Tc-pertechnetate, ^(99m)Tc-redblood cells, ^(99mTc)-white blood cells, ¹²³I-metaiodobenzylguanidine,and ²⁰¹Tl. Complete cessation was suggested for ⁶⁷Ga-citrate,¹²³I-sodium iodide, and ¹³¹I-sodium iodide. The recommendation for ¹²³Iwas based on a 2.5% contamination with ¹²⁵I, which is no longerapplicable.

Representative data of radiation dose estimates for a number ofradiopharmaceuticals commonly used in nuclear medicine; each listed in atable for all major source organs, several other organs typically ofinterest, and the effect of an administered dose (per mCi) of a specificradiopharmaceutical on target organs expressed in rem per mCi, ispresented in Appendix 1 hereinbelow. Data was collected from “RadiationDose Estimates for Radiopharmaceuticals” by Michael G. Stabin, James B.Stubbs and Richard E. Toohey of the Radiation Internal Dose InformationCenter, Oak Ridge Institute for Science and Education, mail stop 51,P.O. Box 117, Oak Ridge, Tenn. 37831-0117.

Although the presently administered doses of radiopharmaceuticals areconsidered safe, there is a great need to substantially reduce theradiation and toxic effects attributed to use of such substances. Due tothe finite sensitivity exhibited by today's imaging probes, currentlyestablished doses of radiopharmaceuticals are at the upper limits ofthose allowed by the NRC.

One inherent limitation of radioactive-emission imaging stems from theweighing of risks and benefits, namely the conflict between therequirement to limit the use of potentially harmful radioactive isotopeson one hand, and the need to generate sufficient photons from thediagnosed subject in order to produce a meaningful image on a camera ordetector of limited sensitivity, on the other. Although low amounts ofsuch radioisotopes are typically administered so as to not exceedrecommended doses, currently available detectors require substantial andpotentially hazardous amounts of radioisotopes in order to efficientlydetect emission. This problem is intensified in cases where a patient isrequired to undergo several diagnostic procedures over the time ofdisease treatment, and more so in cases where the patient is a pregnantwoman, an infant or a child.

Another limitation of the currently used techniques is the relativelyshort time periods which are available to the practitioner to collectdiagnostic nuclear images due to decay of the radioisotopes (mostdiagnostic radiopharmaceuticals are characterized by short half-life),and rapid clearance of the diagnostic radiopharmaceuticals from the bodyby natural bio-processes. Moreover, the rapid decay and clearance of theradiopharmaceuticals prevents sufficient diagnosis of a dynamic systemsuch as the body, wherein a series of images must be taken, so as tocharacterize a constantly changing environment. In these cases, a staticimage will not suffice but rather a series of images, much like in amovie. Again, this limitation could have been partially lessened if highdosage could be administered or images could be collected by moresensitive devices.

Thus, although the presently administered doses of diagnosticradiopharmaceuticals are considered safe there is still a widelyrecognized need for, and it would be highly advantageous to haveradiopharmaceutical kits and methods in which the radiation and toxiceffects of the radiopharmaceuticals are substantially reduced, wherebythe diagnosis quality is at least maintained and desirably improved.

The present inventors have recently devised and constructed single andmulti-collector emission detection probes which have vastly improvedemission collection capabilities which enable highly sensitive and/orshort-termed image capture. These novel emission detection/collectionsystems are at least ten-fold more efficient than presently utilizedsystems (the ratio of measured radiation to emitted radiation is atleast 10 to 100-fold higher than prior art systems). This is primarilydue to the use of either very sensitive radioactivity emission detectorscoupled to high resolution position sensing detectors or to the use ofmultiple scannable detectors, and further to the use of dedicatedalgorithms as is disclosed, for example, in the following internationalapplications: PCT/IL2005/000394, PCT/IL2005/000572, PCT/IL2005/000575,PCT/IL2005/000048, WO20040054248 and WO200216965, the contents of whichare hereby incorporated by reference. These novel systems employemission probes which are highly efficient in collecting emissions andthus enable, in combination with dedicated processing algorithms, moresensitive and accurate emission mapping.

The present inventors have now envisioned that the exceptionalperformance of the abovementioned device, can be efficiently utilized indiagnostic nuclear medicine and imaging, by opening a path to thedesired minimization of exposure to ionizing radiation of patients andstaff members and/or to the desired high resolution imaging.

The present invention relates to diagnostic radiopharmaceutical doseunits and methods of using same in diagnostic nuclear imaging.Specifically, the present invention can be used to image specific tissuesuch as pathological tissue and acquire dynamic imagery while minimizingthe harmful effects of radiation caused by use of ionizing radiationsources in diagnostic radiopharmaceuticals. The present invention canfurther be used to image tissues while utilizing otherwise inefficientradiopharmaceuticals (e.g., having inherent low emission rate) and/or toperform dynamic imagery during short time periods and/or in highresolution.

The principles and operation of the present invention may be betterunderstood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

The use of radioactive substances which produce ionizing radiation isnecessary for advanced methods of pathologic diagnosis and for planningan optimal treatment regime of a growing number of medical conditions.Use of radioactive substances allows the practice of minimally invasivesurgical techniques, which save the patients most of the trauma, pain,suffering, hospitalization, recovery and adverse complicationsassociated with conventional “open surgical” procedures. Yet, the use ofdiagnostic radiopharmaceuticals in diagnostic nuclear medicine isassociated with some risk since it exposes the probed subject as well asthe medical and technical staff to harmful radiation, and further possesthe obligation of expensive and complicated disposal of radioactivematerials.

In view of the above, there is a constant need to minimize the exposureof any subject, to ionizing radiation. This can be achieved byminimizing the amount/concentration of the radioactive substance and/orthe duration of the exposure to the radioactive substance.

A patient undergoing a nuclear medicine procedure will receive aradiation dose. Under present international guidelines it is assumedthat any radiation dose, however small, presents a risk.

An effective dose of a nuclear medicine investigation is typicallyexpressed by units of millisieverts (mSv). The effective dose resultingfrom an investigation is influenced by the amount of radioactivityadministered in megabecquerels (MBq), the physical properties of thediagnostic radiopharmaceutical used (e.g., the type of ionizingradiation, the rate of emission and decay), its distribution in the body(e.g., the accumulation of the emitting agent per tissue) and its rateof clearance from the body. For example, effective doses can range from0.006 mSv for a 3 MBq for ⁵¹Cr-EDTA measurement of glomerular filtrationrate (measurement of the kidneys' waste filtration and removal) to 37mSv for a 150 MBq ²⁰¹Tl non-specific tumor imaging procedure. The commonbone scan with 600 MBq of ^(99m)Tc-MDP has an effective dose of 3 mSv.

As mentioned above, the present inventors have developed a system whichemploys emission probes that are highly efficient in collectingemissions and thus enable, in combination with dedicated processingalgorithms, more sensitive and accurate emission mapping.

These novel systems have encouraged the present inventors to conceivenovel diagnostic kits and diagnosis methods which enable (i)substantially lower diagnostic radiopharmaceutical doses (as comparedwith the presently used doses); (ii) shorter time of exposure (i.e.,collecting the imaging data is a shorter time); (iii) use ofradioisotopes that have short half-life and which are typicallyimpractical when the presently known imaging devices are utilized; and(iv) mapping of organs in which rapid substance clearance is observed,and any combination of the foregoing.

Furthermore, the present inventors hypothesized that the heightenedsensitivity and overall higher efficiency of the data acquisitiondevice, which allows for the shorter exposure time for diagnosticnuclear imaging, will open the possibility of invasive, minimallyinvasive and noninvasive time-resolved imagery, or dynamic imagery ofbiological systems in a living organism.

Thus, the present inventors have now uncovered that the use of suchprobes facilitates the use of substantially lower amounts of diagnosticradiopharmaceuticals than those presently utilized and thus enablespackaging and diagnostic use of novel radiopharmaceutical dose units ofsubstantially lower radioactivity. As is illustrated above, the probeand imaging systems described in previous disclosures of the presentinventors enable, for the first time, use of substantially lower dosesof various diagnostic radiopharmaceuticals in nuclear imaging.

Thus, according to one aspect of the present invention, there isprovided a diagnostic pharmaceutical kit which can be utilized innuclear imaging techniques. The kit contains a packaged dose unit of adiagnostic radiopharmaceutical having an effective dose equivalence(EDE) of 2.5 millirem (mrem) or less per kg body weight of a subject.This packaged dose is considerably lower than the packaged dose of theprior art, and is in line with the general motivation to reduce to aminimum the exposure of the subject to substances which emit ionizingradiation. Preferably, the EDE of the packaged dose unit in accordancewith an aspect of the present invention is 0.01-2 millirem per kg bodyweight of a subject, and more preferably it is 0.01-1 millirem per kgbody weight of a subject.

Similarly, the diagnostic pharmaceutical kit of the present inventioncontains a packaged dose unit of a diagnostic radiopharmaceutical havingan effective dose equivalence (EDE) of 150 millirem (mrem) or less,which is a typical whole-body dose for a 70 kg person. Preferably, theEDE of the packaged whole-body dose unit of in accordance with an aspectof the present invention is 15-100 millirem per 70 kg subject, morepreferably 15-50 millirem per 70 kg subject.

Compared to a typical whole-body dose of ^(99m+)Tc DTPA of 650 mrem fora brain scan according to prior art, a whole-body dose of the presentinvention can be as low as 65 mrem and less; compared to a typicalwhole-body dose of ^(99m)Tc-Sestimibi of 890 mrem for a heart scanaccording to prior art, a whole-body dose of the present invention canbe as low as 89 mrem and less; and compared to a typical whole-body doseof ¹⁸F FDG of 700 mrem for a general somatic scan according to priorart, a whole-body dose of the present invention can be as low as 70 mremand less.

Alternatively, the dose unit can include an amount of a diagnosticradiopharmaceutical which will result in an amount of detected countssufficient for imaging when using the abovementioned imaging devicehaving a heightened sensitivity. In nuclear medicine, the dose in mCi ofa diagnostic radiopharmaceutical can also be determined according to thesensitivity of the detector utilized, the total time of scan and thetotal counts needed for imaging (typically about 2-4×10⁶ for a scannedregion and about 10⁵ for a target organ such as the heart). Theseparameters can be utilized to determine the collection efficiency ofprior art emission detection systems. For example, in a ^(99m)Tc heartscan a typical administered dose is 20-30 mCi of which about 1.2-1.5% to1.5-4% are uptaken by the heart (namely 0.3 mCi-1.2 mCi, typically0.5-1.0 mCi) and a typical scan is conducted for approximately 10minutes (600 seconds). Since a single mCi accounts for 3.7×10⁷ countsper second, the efficiency of a typical detection system calculates toapproximately 1.8 photons captured for every 10,000 photons emitted fromthe organ. Since the present system is at least 10 fold more efficientat photon capturing (e.g., capable of capturing at least 1 photon out ofevery 1000 photons emitted) a tenth of a diagnostic radiopharmaceuticaldose can be utilized for scanning. Thus, for the above describedexample, a packaged dose unit of 2.5 mCi ^(99m)Tc or less can beutilized for imaging a heart over a period of 10 minutes.

Since the dose reaching the target organ (e.g., the heart) is a fractionof the dose administered, for example, and as stated above, in the caseof mapping the cardiac muscle, about 1.5-4% of the dose injectedintravenously (20-30 mCi) reaches the heart (0.3 mCi in the heart),mapping a directly injected dose unit of 0.03 mCi or less is possibleusing the systems developed by the present inventors.

As used herein the phrase “packaged dose unit” refers to a dosage unit(or unit dose) which is packaged in one or more containers such asvials, ampoules or a delivery syringe. Preferably, the dose unit ismanufactured and packaged for inhalation or injection (intravenous orsubcutaneous) according to FDA regulatory guidelines for human use[Rules and Regulations, Federal Register (1999), Vol. 64, No. 94, pp26657-70].

The dose unit may be ready for administration or may require premixingprior to administration. The latter case is exemplified by a radiotracerpreparation which includes an isotope attached to a recognition bindingmoiety such as an antibody, as is detailed hereinbelow.

Adapting to the definition by the FDA [Code of Federal Regulations(2005), Title 21, Vol. 7, CITE: 21CFR601.31], the phrase “diagnosticradiopharmaceutical” refers to (a) an article that is intended for usein the diagnosis or monitoring of a disease or a manifestation of adisease in humans and that exhibits spontaneous disintegration ofunstable nuclei with the emission of nuclear particles or photons; or(b) any non-radioactive reagent kit or nuclide generator that isintended to be used in the preparation of such article as defined in (a)hereinabove.

Radiopharmaceuticals are therefore compounds that include one or moreradioisotopes having such an unstable nuclei.

The term “radioisotope”, refers to a radioactive atom that has aspecific radioactivity above that of the background level for the sameatom. It is well known, in this respect, that naturally occurringelements are present in the form of varying isotopes, some of which areradioactive isotopes. The radioactivity of the naturally occurringelements is a result of the natural distribution of these isotopes, andis commonly referred to as a background radioactive level. However,there are known methods of enriching a certain element with isotopesthat are radioactive. The result of such enrichment is a population ofatoms characterized by higher radioactivity then a natural population ofthat atom, and thus the specific radioactivity thereof is above thebackground level.

A diagnostic radiopharmaceutical can be a compound containing one ormore radioisotopes per se, or, a radiotracer, in which the compound isbound to a recognition moiety, as follows.

In cases where the organ, tissue or cells to be imaged can becharacterized by a known specific and localized (fixed) biochemicalmoieties, such as a peptide, a protein, a receptor, a membrane, aglycan, a nucleic acid (i.e., RNA and/or DNA) or any combinationthereof, the radiopharmaceutical can be designed so as to specificallybind to one or more of these biochemical moieties by way of molecularrecognition. This binding is afforded by virtue of one or morerecognition moieties which form a part of the radiopharmaceutical. Theserecognition binding moieties are selected so as to have a high affinityto the specific biochemical moieties characterizing the target organ,tissue or cells to be imaged. This affinity allows for theradiopharmaceutical to concentrate at the target organ, tissue or cellsat higher rates than the surrounding organs, tissues or cells, therebyaffording an image wherein the target organ, tissue or cells arehighlighted by the contrast of radioactive emission.

Radiopharmaceuticals having such binding moieties which act as a vehiclefor transporting and delivering the radioactive isotope to a specifictarget are referred to herein as radiotracers. Therefore, the term“radiotracer”, as used herein, refers to a radiopharmaceutical havingone or more recognition binding (targeting) moieties attached thereto.

As used herein, the phrase “recognition binding moiety” or “targetingmoiety” refers to a moiety that interacts (binds) with a targetrecognition site by means of molecular recognition, and include, withoutlimitation, a ligand, an inhibitor, a co-factor, an antibody, amonoclonal antibody, an antibody fragment, an antigen, a hapten, areceptor, a receptor affine peptide, a peptide, a protein, a membrane, anucleotide and a nucleic acid.

Molecular recognition, also known as “host-guest chemistry”, is aphenomenon in which molecules are distinguished accurately from othermolecules. Chemically, it indicates that certain molecules abnormallybond with certain molecules and are relatively inert with respect toother molecules found in the same environment. This phenomenon involvesthe three-dimensional positioning of various sub-molecularfunctionalities which can form interactions via reciprocal actions suchas hydrogen bonds, hydrophobic interactions, ionic interactions,aromatic interactions and/or other non-covalent bond interactions andcombination thereof. General examples of molecular recognition includeligand-receptor interactions, enzyme-substrate interactions,antibody-antigen interactions, biotin-avidin affinity interactions andthe like.

Non-limiting examples of commonly used radiotracers include^(99m)Tc-Arcitumomab (CEA-Scan™) which is a monoclonal antibody forimaging colorectal tissues afflicted with colorectal cancer,^(99m)Tc-sestamibi (Cardiolite™) and ^(99m)Tc-tetrofosmin (Myoview™) forimaging the heart of a subject for myocardial perfusion, ¹¹¹In-Capromabpendetide (ProstaScint™) which is a monoclonal antibody for imagingprostate tissues afflicted with prostate cancer, ^(99m)Tc-Fanolesomab(NeutroSpec™) which is a monoclonal antibody for imaging inflamed andinfectious tissues and ⁹⁰Y/¹¹¹In-Zevalin (Ibritumomab Tiuxetan) which isa monoclonal antibody directed against the CD20 antigen, whereby thisantigen is found on the surface of normal and malignant B lymphocytes.

Any diagnostic radiopharmaceutical can be utilized in the kit of thepresent embodiments. In general, the kit of the present embodiments maycontain a reduced radiation dose emitted from each radiopharmaceutical,which ranges from 0.1 of the dose of the prior art to 0.01 of the doseof the prior art.

Exemplary radiopharmaceuticals that can be utilized in this context ofthe present invention include, without limitation, ³H-water, ³H-inulin,¹¹C-carbonmonoxide, ¹³N-ammonia, ¹⁴C-inulin, ¹⁵O—H₂O, ¹⁵I—O₂,¹⁸F-fluorodeoxyglucose, ¹⁸F-sodium fluoride, ⁵¹Cr-erythrocytes (RBC),⁵⁷Co-vitamin B₁₂ (cyanocobalamin), ⁵⁸Co-vitamin B₁₂ (cyanocobalamin),⁵⁹Fe-citrate, ⁶⁰Co-vitamin B₁₂ (cyanocobalamin), ⁶⁷Ga-citrate,⁶⁸Ga-citrate, ⁷⁵Se-selenomethionine, ^(81m)Kr-krypton for inhalation,oral administration or injections, ⁸²Rb, ⁸⁵Sr-nitrate,⁹⁰Y/¹¹¹In-ibritumomab tiuxetan (⁹⁰Y/¹¹¹In-Zevalin), ^(99m)Tc-albuminmicrospheres, ^(99m)Tc-disofenin, lidofenin and mebrofenin,^(99m)Tc-DMSA, ^(99m)Tc-DTPA (injection), ^(99m)Tc-DTPA (aerosol),^(99m)Tc-ECD (ethylene cystate dimer), ^(99m)Tc-exametazime (HMPAO),^(99m)Tc-glucoheptonate, ^(99m)Tc-HEDP, ^(99m)Tc-HMDP, ^(99m)Tc-HSA,^(99m)Tc-MAA, ^(99m)Tc-MAG₃, ^(99m)Tc-MDP, ^(99m)Tc-tetrofosmin(Myoview), ^(99m)Tc-sestamibi (Cardiolite), ^(99m)Tc-oraladministrations, ^(99m)Tc-pertechnetate, ^(99m)Tc-pyrophosphate,^(99m)Tc-RBC in vitro and in vivo labeling, ^(99m)Tc-sulfur colloid,^(99m)Tc-teboroxime, ^(99m)Tc-white blood cells, ¹¹¹In-ibritumomabtiuxetan (¹¹¹In-Zevalin), ¹¹¹In-DTPA, ¹¹¹In-platelets, ¹¹¹In-RBC,¹¹¹In-white blood cells, ¹²³I-hippuran, ¹²³I-IMP, ¹²³I-mIBG, ¹²³I-sodiumiodide, ¹²⁴I-sodium iodide, ¹²⁵I-fibrinogen, ¹²⁵I-IMP, ¹²⁵I-mIBG,¹²⁵-sodium iodide, ¹²⁶I-sodium iodide, ¹³⁰I-sodium iodide,¹³¹I-hippuran, ¹³¹I-HSA, ¹³¹I-MAA, ¹¹³I-mIBG, ¹³¹I-Rose Bengal,¹³¹I-sodium iodide, ¹²⁷Xe-inhalation and injection, ¹³³Xe-inhalation andinjection, ¹⁹⁷Hg-chlormerodrin, ¹⁹⁸Au-colloid and ²⁰¹Tl-chloride.

Following are several non-limiting examples of the radioactive dose ofexemplary radiopharmaceuticals utilized in accordance with this aspectof the present invention. Since an administered dose is typicallymeasured in mCi activity of the radioisotope, the following lists theradioactivity of a packaged dose unit in the kit of the presentembodiments, compared to the radioactivity of the presently used doses.

Radioactive ammonia typically comprises a ¹³N isotope having a half-lifeof 9.96 minutes. A radioactive dose of ¹³N-ammonia is typically 20 mCi.According to a preferred embodiment of the present invention, aradiopharmaceutical kit comprises a radioactive dose of ¹³N-ammonia thatranges from 5 mCi to 0.01 mCi, more preferably from 2 mCi to 0.02 mCiand thus can be, for example, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02 or 0.01mCi.

Radioactive fluorodeoxyglucose (FDG) typically comprises an ¹⁸F isotopehaving a half-life of 110 minutes. A radioactive dose of ¹⁸F-FDG istypically 10 mCi. According to a preferred embodiment of the presentinvention, a radiopharmaceutical kit comprises a radioactive dose of¹⁸F-FDG that ranges from 3 mCi to 0.1 mCi, more preferably from 1 mCi to0.1 mCi and thus can be, for example, 3, 1 or 0.1 mCi.

Radioactive capromab pendetide (ProstaScint), typically comprises an¹¹¹In isotope having a half-life of 72 hours. A radioactive dose of¹¹¹In-capromab pendetide is typically 5 mCi. According to a preferredembodiment of the present invention, a radiopharmaceutical kit comprisesa radioactive dose of ¹¹¹In-capromab pendetide that ranges from 2 mCi to0.01 mCi, more preferably from 0.5 mCi to 0.01 mCi and thus can be, forexample, 2, 1, 0.5, 0.1, 0.05 or 0.01 mCi.

Radioactive WBCs (non-protein peptide), typically comprises an ¹¹¹Inisotope. A radioactive dose of ¹¹¹In-WBCs is typically 0.5 mCi.According to a preferred embodiment of the present invention, aradiopharmaceutical kit comprises a radioactive dose of ¹¹¹In-WBCs thatranges from 0.2 mCi to 0.001 mCi, more preferably from 0.05 mCi to 0.001mCi and thus can be, for example, 0.2, 0.1, 0.05, 0.01, 0.005 or 0.001mCi.

Radioactive Satumomab Pendetide (OncoScint), typically comprises an¹¹¹In isotope. A radioactive dose of ¹¹¹In-Satumomab Pendetide istypically 5 mCi. According to a preferred embodiment of the presentinvention, a radiopharmaceutical kit comprises a radioactive dose of¹¹¹In-Satumomab Pendetide that ranges from 2 mCi to 0.01 mCi, morepreferably from 0.2 mCi to 0.01 mCi and thus can be, for example, 2, 1,0.5, 0.1, 0.05 or 0.01 mCi.

Radioactive Pentetreotide typically comprises an ¹¹¹In isotope. Aradioactive dose of ¹¹¹In-Pentetreotide is typically 6 mCi. According toa preferred embodiment of the present invention, a radiopharmaceuticalkit comprises a radioactive dose of ¹¹¹In-Pentetreotide that ranges from1 mCi to 0.005 mCi, more preferably from 0.5 mCi to 0.005 mCi and thuscan be, for example, 1, 0.5, 0.2, 0.1, 0.05, 0.01 or 0.005 mCi.

Radioactive Arcitumomab typically comprises a ^(99m)Tc isotope having ahalf-life of 6 hours. A radioactive dose of ^(99m)Tc-Arcitumomabtypically ranges from 20 mCi to 30 mCi. According to a preferredembodiment of the present invention, a radiopharmaceutical kit comprisesa radioactive dose of ^(99m)Tc-Arcitumomab that ranges from 5 mCi to0.05 mCi, more preferably from 3 mCi to 0.05 mCi and thus can be, forexample, 5, 2, 1, 0.5, 0.1 or 0.05 mCi.

Radioactive Sodium pertechnetate typically comprises a ^(99m)Tc isotope.A radioactive dose of ^(99m)Tc-Sodium pertechnetate typically rangesfrom 10 mCi for a whole-body scan to 0.1 mCi, whereby the packaged doseunit is typically formulated as a drop for an eye scan. According to apreferred embodiment of the present invention, a radiopharmaceutical kitcomprises a radioactive dose of ^(99m)Tc-Sodium pertechnetate thatranges from 5 mCi to 0.01 mCi, more preferably from 1 mCi to 0.01 mCiand thus can be, for example, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02 or 0.01mCi.

A radioactive dose of Erythrocytes (RBC) comprising a ^(99m)Tc isotopetypically ranges from 10 mCi to 25 mCi. According to a preferredembodiment of the present invention, a radiopharmaceutical kit comprisesa radioactive dose of ^(99m)Tc-RBC that ranges from 5 mCi to 0.05 mCi,more preferably from 1 mCi to 0.05 mCi and thus can be, for example, 5,2, 1, 0.5, 0.1, 0.05, 0.02 or 0.01 mCi.

Radioactive Depreotide (NeoTect), apcitide (AcuTect), pyrophosphate,medronate (MDP), exametazime (HMPAO) and bicisate (ECD, Neurolite) allcomprise a ^(99m)Tc isotope. A radioactive does of theseradiopharmaceuticals is typically 20 mCi. According to a preferredembodiment of the present invention, radiopharmaceutical kits comprise aradioactive dose of such a ^(99m)Tc-radiopharmaceuticals that rangesfrom 5 mCi to 0.05 mCi, more preferably from 1 mCi to 0.05 mCi and thuscan be, for example, 5, 2, 1, 0.5, 0.2, 0.1, 0.05 mCi.

A radioactive dose of ^(99m)Tc-Sestamibi typically ranges from 10 mCi(for stress) to 30 mCi (for rest). According to a preferred embodimentof the present invention, a radiopharmaceutical kit comprises aradioactive dose of such a ^(99m)Tc-radiopharmaceutical that ranges from5 mCi to 0.01 mCi, more preferably from 1 mCi to 0.01 mCi and thus canbe, for example, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02 or, 0.01 mCi.

Radioactive Cyanocobalamin typically comprises an ⁵⁷Co isotope having ahalf-life of 271.8 days. A radioactive dose of ⁵⁷Co-Cyanocobalamin istypically 0.001 mCi. According to a preferred embodiment of the presentinvention, a radiopharmaceutical kit comprises a radioactive dose of⁵⁷Co-Cyanocobalamin that ranges from 0.0003 mCi to 0.00001 mCi, morepreferably from 0.0001 mCi to 0.00001 mCi and thus can be, for example,0.0003, 0.0001, 0.00005 or 0.00001 mCi.

Radioactive Gallium Citrate, typically comprises a ⁶⁷Ga isotope having ahalf-life of 271.8 days. A radioactive dose of ⁶⁷Ga-Gallium citrate istypically 5 mCi for PET imaging and 10 mCi for SPEC imaging. Accordingto a preferred embodiment of the present invention, aradiopharmaceutical kit comprises a radioactive dose of ⁶⁷Ga-Galliumcitrate that ranges from 1 mCi to 0.01 mCi, more preferably from 0.5 mCito 0.01 mCi and thus can be, for example, 1, 0.5, 0.2, 0.1, 0.05 or 0.01mCi. ⁸¹Kr isotope, having a half-life of 210,000 years, is presentlyused as a gas for dynamic imaging. A radioactive dose of ⁸¹Kr istypically 10 mCi. According to a preferred embodiment of the presentinvention, a radiopharmaceutical kit comprises a radioactive dose of⁸¹Kr that ranges from 2 mCi to 0.05 mCi, more preferably from 1 mCi to0.05 mCi and thus can be, for example, 2, 1, 0.5, 0.1 or 0.05 mCi.

Radioactive sodium iodide typically comprises an ¹²³I isotope having ahalf-life of 13.2 hours. A radioactive dose of ¹²³I-sodium iodidetypically ranges from 0.1 mCi to 0.4 mCi, and the radiopharmaceuticaldose unit is often provided in capsules. According to a preferredembodiment of the present invention, a radiopharmaceutical kit comprisesa radioactive dose of ¹²³I-sodium iodide that ranges from 0.05 mCi to0.001 mCi, more preferably from 0.01 mCi to 0.001 mCi and thus can be,for example, 0.1, 0.05, 0.02, 0.01, 0.005 or 0.001 mCi, whereby the¹²³I-sodium iodide can be packaged as capsules.

Radioactive Sodium iodide can alternatively comprise an ¹³¹I isotopehaving a half-life of 8 days. A radioactive does of ¹³¹I-sodium iodidetypically ranges from 0.01 mCi to 0.004 mCi. According to a preferredembodiment of the present invention, a radiopharmaceutical kit comprisesa radioactive dose of ¹³¹I-sodium iodide that ranges from 0.001 mCi to0.00005 mCi, and thus can be, for example, 0.001, 0.0005, 0.0002, 0.0001or 0.00005 mCi, whereby the ¹³¹I-sodium iodide can be packaged ascapsules.

Radioactive albumin typically comprises an ¹²⁵I isotope having ahalf-life of 59.4 days. A radioactive does of ¹²⁵I-albumin is typically0.02 mCi. According to a preferred embodiment of the present invention,a radiopharmaceutical kit comprises a radioactive dose of ¹²⁵I-albuminthat ranges from 0.005 mCi to 0.0001 mCi, more preferably from 0.001 mCito 0.0001 mCi and thus can be, for example, 0.005, 0.002, 0.001, 0.0005or 0.0001 mCi.

Radioactive sodium chromate typically comprises a ⁵¹Cr isotope having ahalf-life of 27.7 days. A radioactive dose of ⁵¹Cr-sodium chromatetypically ranges from 0.15 mCi to 0.3 mCi. According to a preferredembodiment of the present invention, a radiopharmaceutical kit comprisesa radioactive dose of ⁵¹Cr-sodium chromate that ranges from 0.05 mCi to0.001 mCi, more preferably from 0.01 mCi to 0.001 mCi and thus can be,for example, 0.05, 0.02, 0.01, 0.005 or 0.001 mCi.

As is provided in the list above, the mCi dose range of the present doseunit of each listed exemplary diagnostic radiopharmaceutical issubstantially lower than that of prior art dose units.

The kit of the present embodiments can be used with any suitable nuclearimaging technique, examples of which are provided in Appendix 1hereinafter.

The radiopharmaceutical of the diagnostic kit of the present embodimentscan be prepared using any suitable prior art approach. Such approachesare well known to the ordinary skilled artisan and as such no furtherdescription of specific synthesis approaches of diagnosticradiopharmaceuticals and in particular radiotracers are provided herein.

However, in cases where the radiopharmaceutical is a radiotracer, it issometimes preferred that the isotope be provided separate from therecognition binding moiety especially in cases of isotopes exhibiting ashort half life, since a specific activity of such a radiotracerpreparation will substantially decrease over a short time period.

As mentioned hereinabove, an effective dose of any givenradiopharmaceutical is influenced, among other factors, by the amount ofthe radioisotope and the state of decay of the radioisotope, namely theradioactivity which is currently measured at any given time. In essence,an isotope which already decayed no longer contributes to the activityof the administered sample, and therefore is considered an impurity. Inaddition, radiopharmaceuticals which contain chelators or recognitionmoieties attached thereto may decompose, both in vivo and in vitro, soas to produce, for example, the radioisotope, the chelating moietyand/or the recognition moiety. The free chelators and recognitionmoieties are also considered impurities.

Radioisotopes utilized for synthesis are therefore typically >60% pure,and preferably are >90% pure; during radiotracer synthesis, arecognition binding moiety is mixed with a radioisotope and quality ischecked to maintain approximately a 95% pure composition of theradiotracer. The remaining 5% is composed of non-radioactive isotopes,chelators, recognition moieties and the like.

Following mixing and prior to injection, isotope decay and chemicaldecomposition may reduce the specific activity of the diagnosticradiopharmaceutical in proportion to isotope decay time and theinstability of the radiopharmaceutical.

Few diagnostic radiopharmaceuticals depend on “specific activity” orpurity, since they “compete” for receptors with their decompositionproducts or their decomposition products produce adverse effects (e.g.to lungs).

The kit of the present invention can further include instructions foruse in carrying out a nuclear scan as well as instructions for handlingand additional packaging materials (e.g. pig) as required by federalregulations. Radioisotopes must be carefully handled, therefore vials orsyringes containing such substances are delivered inside containersoffering some degree of radiation shielding. Furthermore, governmentregulations require syringes to be disposed of in a disposal containerthat shields others from the risk of injury posed by their sharp,biologically-contaminated hypodermic needles. Such a container generallyreferred to herein as a “sharps” container, typically has an innercavity or chamber that can hold one or more syringes.

One type of conventional delivery container currently used for thedelivery of syringes containing radioactive drugs is known as aradiopharmaceutical pig. The radiopharmaceutical pig has a shieldedinner chamber suitable for enclosing a syringe that is itself heldinside of a sharps container. In particular, the chamber is lined withelemental lead to shield individuals from the radioactive drug in thesyringe. The exterior of the radiopharmaceutical pig is a plasticpolystyrene shell. The sharps container has an insert and a cap that canbe engaged by two snaps that fit into two aligned slots formed on theinsert.

Prior to administration, the syringe is loaded with the required dose ofa radioactive drug and is placed in the insert, which is nested in thechamber of the radiopharmaceutical pig. The radiopharmaceutical pig isthen closed and delivered to the hospital, whereupon the pig isdisassembled and the syringe is used to inject the dose into thepatient. The spent syringe may then be placed back into the sharpsinsert and the cap may then be placed on the housing to hold the spentsyringe within the sharps container. The radiopharmaceutical pig isreassembled and taken to a disposal area, which may or may not be at thepharmacy.

While exposure to ionizing radiation presents a major, widely recognizedlimit to the presently known nuclear imaging techniques, thesetechniques are oftentimes limited by other factors. These include, forexample, rapid decay of the radioisotope (i.e., short half-life), rapidclearance of the radiopharmaceutical from the targeted organ, and lowenergy and/or rate of disintegration of the radiopharmaceutical.

These characteristics determine the amount and energy of detectablephotons which reach the detector per time unit. When used with thepresently known emission detectors, low amount and/or energy of thedetectable photons results in a weak or no signal and hence fail toprovide a meaningful image. Thus, for example, radioisotopes thatrapidly decay or are rapidly cleared from the target organ, fail toproduce a sufficient amount of detectable photons at the time of datacollection.

According to embodiments of the present invention, the highly sensitiveemission detector designed by the present inventors can be used todetect sufficient photons from such radioisotopes due to its higherefficiency and wider dynamic range, even for radioisotope characterizedby a short half-life, low rate and low energy of disintegration, whichmay or may not be combined with a low rate of accumulation in the organof interest and a rapid clearance from the body by metabolic andchemical processes.

The present inventors have now uncovered that the high sensitivity ofthe novel imaging probes described above can be used, due to higherefficiency and wider dynamic range, to collect sufficient imaging dataeven in cases of radiopharmaceuticals that are characterized by lowamount and/or energy of the emitted photons within a time frame of anuclear investigation. Thus, these highly sensitive probes enable toperform efficient imagery even with such radiopharmaceuticals that areincompatible or at least inefficient when utilized with the presentlyknown techniques. These radiopharmaceuticals are collectively referredto herein as having an inherent low emission rate, as this phrase isdefined hereinbelow.

Thus, according to another aspect of the present invention there isprovided a radiopharmaceutical kit which comprises a packaged dose unitof a radiopharmaceutical that have an inherent low emission rate.

The phrase “inherent low emission rate”, as used herein, definesradiopharmaceuticals that emit such levels of radiation which are toolow for producing a useful image under presently used nuclear imagingtechniques due to physical, chemical and biological characteristicswhich render them incompatible or impractical for use with presentlyavailable emission detectors.

The characteristics accounting for inherent low emission rate ofradiopharmaceuticals include, for example, a rapid decay (i.e. shorthalf-life), low disintegration rate, low energy of disintegration of theradioisotope, rapid clearance from the body, and any combination of theforegoing.

Thus, in one embodiment of this aspect of the present invention, theinherent low emission rate of the radiopharmaceutical stems from rapidclearance of the radiopharmaceutical from the body.

The phrase “rapid clearance”, as used herein, encompasses any chemicalor biological process involved in reducing the amount of theradiopharmaceutical in both the targeted organ and the body. This phraseis therefore used herein to describe the bioavailability of theradiopharmaceutical in terms of the rate of its accumulation in a targetorgan, the rate of its clearance from the target organ, the rate of itsdecomposition in the body and the rate of its excretion from the system.

The bioavailability of a given radiopharmaceutical therefore determinesthe time required for the radiopharmaceutical to reach and accumulate inthe organ of interest, the affinity of the radiopharmaceutical to itstarget (in cases where the radiopharmaceutical is a radiotracer) and therate of clearance of the radiopharmaceutical from the body.

Slow accumulation in the tissue of interest and rapid clearance from thebody are adverse effects for any beneficial pharmaceutical, drug and inthe present invention, of any radiopharmaceutical, as the body ridsitself from the foreign substance by means of metabolic processes,natural toxic waste disposal as in the kidneys, and other secretionmechanisms. In radiopharmacology, this problem becomes even moredetrimental as the requirement to have a sufficient amount of thesubstance in its radioactive form in the body for a sufficient durationfor data collection, is opposed by the combination of rapid clearanceand chemical decomposition.

According to this embodiment of the present invention, the kit comprisesa radiopharmaceutical that has a clearance rate that ranges from severalminutes to several days.

According to another embodiment of this aspect of the present invention,the inherent low emission rate of the radiopharmaceutical stems fromrapid decay of the radiopharmaceutical.

As discussed hereinabove, the half-life time of some diagnosticradiopharmaceuticals is very short, in the order of seconds to minutesand the scanning time of such radiopharmaceuticals is therefore alwayslimited. Following a short scanning time-window, no further imagingbenefits are derived from additional scanning since rapid decay resultsin a small fraction of emitting isotopes.

A rapid decay of a radiopharmaceutical typically results from aninherent short half-life of the radioisotope included in theradiopharmaceutical.

Exemplary radioisotopes which have relatively short half-life whichrenders them impractical for use with currently available emissiondetectors, and which can be efficiently utilized according toembodiments of the present invention include, without limitation, ³⁹Clhaving a half-life of 55.6 minutes; ⁶⁹Zn having a half-life of 56minutes; ³⁸S having a half-life of 2.84 hours; ⁵⁶Mn having a half-lifeof 2.579 hours; ⁴⁹Cr having a half-life of 42.3 minutes; and ⁸³Br havinga half-life of 2.40 hours.

According to another embodiment of this aspect of the present invention,the inherent low emission rate of the radiopharmaceutical stems from lowenergy of disintegration of the radiopharmaceutical.

According to another embodiment of this aspect of the present invention,the inherent low emission rate of the radiopharmaceutical stems from lowrate of disintegration of the radiopharmaceutical.

Each of the radiopharmaceutical kits described herein can be efficientlyutilized for obtaining nuclear images of tissue and organs of interest,by employing non- or minimally invasive techniques in vivo.

Thus, according to an additional the present invention there is provideda method of imaging a tissue of a subject. The method is effected byadministering to the subject, either systemically or locally, a doseunit of a diagnostic radiopharmaceutical having a dose equivalent of 2.5mrem or less per kg body weight, as detailed hereinabove; collecting theemission produced by the diagnostic radiopharmaceutical, as detailedhereinbelow; and translating the emission data collected into atwo-dimensional or three-dimensional image data.

Typically, the radiopharmaceutical is administered systematically inorder to achieve two main goals, a) reach the target organ which istypically out of reach when using noninvasive or minimally invasivetechniques, and b) in order to create the appropriate background for theorgan to be imaged and obtain the contrast between the areas of interest(those serving as targets for the radiopharmaceutical) and theirsurrounding. Systematic administration can be effected, for example, byintravenous injection, by inhalation or orally.

As the use of the abovementioned high sensitivity emission detectorbecomes available, the limitations associated with low signal arealleviated considerably. Thus, imaging of tissues or organs usingradiopharmaceuticals that have low emission rate and hence presentlylead to collection of insufficient data during a scan, is facilitated.

Thus, according to another aspect of the present invention, there isprovided another method of imaging a tissue of a subject. The method,according to this aspect of the present invention is effected byadministering to the subject, either systemically or locally, a doseunit of a radiopharmaceutical which is characterized by an inherent lowemission rate, as detailed hereinabove; collecting the emission producedby the diagnostic radiopharmaceutical; and translating the emission datacollected into a two-dimensional or three-dimensional image data.

The method, according to this aspect of the present invention, thereforeallows to use radiopharmaceuticals and to image organs and/or tissuesthat are otherwise impractical.

The high sensitivity of the emission detector taught by the presentinventors further enables to collect sufficient image data in a shorttime period. This feature is exceptionally advantageous since it allowsto minimize the time during which a subject is exposed to radiation.Hence, using any diagnostic radiopharmaceuticals, including theradiopharmaceuticals described herein, nuclear imaging can be performedduring a shorter time period, compared to the presently known imagingmethods.

Thus, according to a further aspect of the present invention there isprovided a method of imaging a tissue, which is effected byadministering to the subject a dose unit of a diagnosticradiopharmaceutical; collecting emission of the diagnosticradiopharmaceutical during a time period that does not exceed, e.g.,1-30 minutes; and translating the emission collected into image data.

The method according to this aspect of the present invention isparticularly advantageous in PET and SPECT imaging techniques.

Positron Emission Tomography (PET), is a nuclear medicine imaginetechnology which requires the administration to a subject of a moleculelabeled with a positron-emitting nuclide. Single Photon EmissionComputed Tomography (SPECT) is a form of chemical imaging in whichemissions from radioactive compounds, labeled with gamma-emittingradionuclides, are used to create cross-sectional images ofradioactivity distribution in vivo.

These techniques require relatively high emission levels for obtaining ameaningful image. In addition, radiopharmaceuticals that are suitablefor use in these techniques are often characterized by relatively shorthalf-lives. Thus, for example, ¹⁵O, ¹³N, ¹¹C and ¹⁸F, which are oftenused in PET, have half-lives of 2, 10, 20, and 110 minutes,respectively. Due to the high emission level required and the shorthalf-lives of the radiopharmaceuticals, relatively high radiation dosesof the radiopharmaceutical are administered to the subject.

Performing such nuclear imaging procedures in relatively short timeperiods is therefore exceptionally beneficial since it reduces the timethe subject is exposed to high radiation level.

The ability to obtain all the required data during a short time period,which is not possible with other currently used detectors, furtherallows the investigator to collect several consecutive images duringthat time scan in which the emission rate is still sufficient forsignificant data collection.

These consecutive images can be used to provide time-resolved data ofthe tissue or organ of interest, showing the development in time ofimaged system.

Thus, according to preferred embodiments of the present invention, forany of the methods described herein, a time-resolved data can beobtained by performing consecutive images of the investigated tissue.

Nuclear imaging techniques suffer from other limitations which arerelated to a weak signal or a low signal-to-noise ratio. Suchlimitations stem from the fact that any detector has a limitedsensitivity, and at any dose of the radiopharmaceutical, only a fractionof the emitted radiation can be picked-up by the detector and/or bedistinguished from the background noise.

Using the improved emission detector taught by the present invention canfurther enable and facilitate the provision of a high-resolution imageof a tissue, which so far was impossible, difficult or requiredexceptionally high doses of the radiopharmaceutical and/or prolongedexposure of the subject to the radiopharmaceutical t.

Thus, according to an aspect of the present invention, there is provideda method of obtaining a high-resolution image of a tissue of a subject.

Any suitable extracorporeal or intracorporeal imaging techniqueemploying any suitable probe types can be used to image the administereddiagnostic radiopharmaceutical in the methods described herein.Preferably an imaging system employing a probe having a wide angle or awide view of collection is employed.

Further preferably, the emission data is collected by one or moreradioactive-emission probes which are characterized by a collectionefficiency of 1%, each of which is separately adjustable within itshousing.

Further preferably, the radioactive-emission probes, or emissiondetectors are scintillation probes which have a collection angle thatenables a collection target area of 15 mm² when placed 15 cm away fromthe target area.

Extra and intra-corporeal probe types which are highly suitable for usewith the kit of the present invention are described in detail in the PCTapplications referenced hereinabove.

A non-limiting example of a widely used radiopharmaceutical,^(99m)Tc-sastamibi, is used herein to demonstrate the various novelfeatures of the present invention. ^(99m)Tc is characterized by ahalf-life (t_(1/2)) of 6.02 hours. Table 3 below presents the physicaldecay of ^(99m)Tc, wherein the calibration time is set to 0 arbitrarilyand the activity is defined as 100%. The remaining fraction ofradioactivity is recorded every hour from that time point. This decaychart is used by the medical staff when preparing the sample forinjection into a patient undergoing diagnostic imaging. The absoluteactivity of the product is measured at the manufacturer site on the dayof shipment, and the complete assay data is provided on the tag attachedto the vial.

TABLE 3 Hours Fraction remaining 0 1.000 (100%) 1 0.891 (89.1%) 2 0.794(79.4%) 3 0.708 (70.8%) 4 0.631 (63.1%) 5 0.562 (56.2%) 6 0.501 (50.1%)7 0.447 (44.7%) 8 0.398 (39.8%) 9 0.355 (35.5%) 10 0.316 (31.6%) 110.282 (28.2%) 12 0.251 (25.1%)

Apart for radioactivity decay, the product is cleared from the body bynatural processes. Myocardial uptake which is coronary flow dependent is1.2% of the injected dose at rest and 1.5% of the injected dose atexercise. Table 4 below illustrates the biological clearance as well aseffective clearance which include biological clearance and radionuclidedecay of ^(99m)Tc-Sestamibi from the heart and liver.

TABLE 4 Rest Stress Time Heart Liver Heart Liver (minutes) BiologicalEffective Biological Effective Biological Effective Biological Effective5 1.2 1.2 19.6 19.4 1.5 1.5 5.9 5.8 30 1.1 1.0 12.2 11.5 1.4 1.3 4.5 4.260 1.0 0.9 5.6 5.0 1.4 1.2 2.4 2.1 120 1.0 0.8 2.2 1.7 1.2 1.0 0.9 0.7240 0.8 0.5 0.7 0.4 1.0 0.6 0.3 0.2

The agent is excreted without any evidence of metabolism. The majorpathway for clearance of ^(99m)Tc-Sestamibi is the hepatobiliary system.Activity from the gall bladder appears in the intestines within one hourof injection. Twenty-seven percent of the injected dose is excreted inthe urine, and approximately thirty-three percent of the injected doseis cleared through the feces in 48 hours.

A typical published preparation procedure of ^(99m)Tc-Sestamibi[CARDIOLITE®, Kit for the Preparation of Technetium Tc99m Sestamibi forInjection, Document No. 513121-0300, March 2000, DuPont PharmaceuticalsCompany, Billerica, Mass., USA] includes transferring a known volume ofa solution containing the radioactive isotope sodium salt into a vialcontaining the rest of the ingredients, including the MIBI (2-methoxyisobutyl isonitrile) component. This amount should correspond to925-5550 MBq (25-150 mCi) in approximately 1 to 3 ml. After heating thereaction mixture, the reaction vial sample is assayed using a suitableradioactivity calibration system, and the results of the assay determinethe amount which will be injected into the patient. According to thisprior art procedure, the prepared product should be stored at 15-25° C.before and after reconstitution and used within 6 hours afterpreparation. The patient dose and radiochemical purity (see theabove-mentioned Document No. 513121-0300 for procedures) should bemeasured by a suitable radioactivity calibration system immediatelyprior to patient administration.

As can be deduced from the above description, there are two majorphysical attributes which determine the time regime for the nuclearimaging process which are crucial for its effectiveness: the rate ofdecay and the rate of clearance.

According to aspects of the present invention, the above procedure canbe altered in two principle ways; one addresses the decay chronology andthe other addresses the quantity required for effective imaging of therelevant organ in the patient. Since the sensitivity of the emissiondetector associated with aspects of the present invention is 10-100folds higher than the currently used detectors, a kit according to theseaspects of the present invention may contain a smaller amount of theradioactive isotope to be used, or may allow a longer time for datacollection after administration, as compared to the presently knownkits. The latter allows for data collection of dynamic processes whichtake place in the patient, i.e., following in-vivo changes in the organswhich are monitored by the nuclear imaging technique, hence allowing fortime-resolved analysis of the medical condition of interest.

Other examples for the preparation procedure of any commerciallyavailable radiopharmaceutical and radiotracer can be in the instructiondocuments provided in presently available kits, such as the kit for thepreparation of ¹¹¹Indium Capromab Pendetide. ¹¹¹Indium CapromabPendetide is a radiotracer containing a murine monoclonal antibody,7E11-C5.3 (the site-specific delivery vehicle), which is covalentlyconjugated to the linker-chelator,glycyl-tyrosyl-(N,-diethylenetriaminepentaacetic acid)-lysinehydrochloride (GYK-DTPA-HCl). The 7E11-C5.3 antibody is of the IgG1,kappa subclass (IgG1K). This antibody is directed against a glycoproteinexpressed by prostate epithelium known as prostate specific membraneantigen (PSMA). The PSMA epitope recognized by monoclonal antibody (MAb)7E11-C5.3 is located in the cytoplasmic domain. The radioisotope ¹¹¹Inis brought in contact with the antibody-linker-chelator conjugate uponpreparation of the sample prior to administration, and the indium istherefore incorporated into the site-specific delivery vehicle. Detailedquantities, characteristics and procedures for the preparation of thisradiotracer for administration can be found inhttp://www.cytogen.com/professional/prostascint/pi.php.

As in the example of ^(99m)Tc-sestamibi, ¹¹¹Indium capromab pendetide(ProstaScint®) is provided as a two-vials kit which contain all of thenon-radioactive ingredients necessary to produce a single unit dose of¹¹¹In ProstaScint®, an immunoscintigraphic agent for administration byintravenous injection only. The ProstaScint® vial contains 0.5 mg ofcapromab pendetide in 1 ml of sodium phosphate buffered saline solutionadjusted to pH 6; a sterile, pyrogen-free, clear, colorless solution.The vial of sodium acetate buffer contains 82 mg of sodium acetate in 2ml of water for injection adjusted to pH 5-7 with glacial acetic acid;it is a sterile, pyrogen-free, clear, and colorless solution. The sodiumacetate solution must be added to the sterile, non-pyrogenic high purity¹¹¹InCl solution to buffer it prior to radiolabeling ProstaScint®. Theimmunoscintigraphic agent ¹¹¹In capromab pendetide is formed afterradiolabeling with ¹¹¹In.

Expert System

The following describes a method, based on imaging a patient usingmultiple kinetic parameters and measuring the distance betweenrespective kinetic parameters, to relate the patient or individualvoxels or groups of voxels to existing groups or populations, which areavailable in a database, thereby arriving at a decision, regarding thepatient or individual voxels or groups of voxels. The existingpopulations in the database may be populations of generally healthyindividuals, or are previous measurements of the same patient.

A platform is provided, which carries out a two-fold function in termsof three-dimensional images. First of all the platform sets up databasesof parameter behavior from populations or from individuals and secondlyit uses those databases to make inferences about a current image inlight of knowledge from the databases. That is to say the platformdecides which group in the database the current measurements mostclosely belong to. The body image obtains voxels and the voxels storemultiple dimensional data therein. For example, a single voxel may storevalues of multiple parameters for a given location in the body andfurthermore, for individual parameters, the voxel may store the timevarying behavior of that parameter over the duration of the image.

The platform may then use the multiple dimensional data in the voxels toidentify behavior, and decide on grouping, and an extension of theplatform may make inferences or decisions as will be described ingreater detail below. The grouping may identify pathology or tissue typeor other group parameters as will be explained below and then the expertsystem may use rules to make decisions say about further treatment ofthe individual. Grouping may be of individual voxels to tissue types, orabout groups of voxels as belonging to a particular tissues and/orpathology and/or organ, or about a pathology shown in the image as awhole.

In general, the different parameters in the voxel are not independent,since they all relate to the same tissue in the same person. Rather,certain parameters tend to correlate with one another. Thus if a certainparameter changes in a certain way we may expect, with a certain levelof probability, that one of the other parameters will also behave in acertain way. Thus a healthy membrane regulates flow of any fluid, and anunhealthy membrane provides little regulation, so that a certainpathology would affect numerous flow parameters.

A scoring system can be used to decide if a pattern that emerges, forexample, from the behavior of one or more parameters, indicates healthytissue or fits a particular pathology. Alternatively, the scoring systemcan be used to decide what tissue type is being viewed.

More particularly, it is possible, given a matrix of voxels withmulti-dimensional kinetic parameters representing a three-dimensionalimage scan over time, and similar matrices from a database, to define acovariance matrix between the two. The covariance matrix can be used tomeasure a statistical distance between the two matrices. The distancemay be computed to numerous matrices in the database and the currentscan can be assigned a parameter represented by the matrix to which itis closest. Thus, given a vector X of test K taken under condition L,the set may be found to be closest to a database set which representssubjects suffering from early symptoms of heart disease. It maytherefore be assumed that the present patient is suffering from heartdisease and the expert system may recommend a treatment regime.Alternatively the comparison may be with tissue types and particularvoxels can be for tissue type, for example, heart tissue.

Certain tissues may, for example, be hard to distinguish. For exampletumor tissue may look like muscular tissue under certain tests. In theevent of such an ambiguity, a deciding test could be applied.

Reference is now made to FIG. 107, which illustrates a procedure forusing a covariance matrix in the kind of platform described above inorder to make inferences. As explained, a database is set up in stage8000 to show existing data. The database is built up over time overdifferent populations of patients or volunteers or for specificpopulations or even for the patient himself. The data sets arepreferably normalized to give a standard presentation of the data sothat they can be compared. Thus a reference average brightness value maybe used or a reference orientation or a reference set of co-ordinatesmay be used, for example.

The database can be constructed using any combination of healthyvolunteers and patients, who may be tested under different environmentalsituations, for example, physical stress, sensory stress, etc.Alternatively the database may comprise tests carried out on the patienthimself using data taken at an earlier time, if such data is available.

The database may comprise matrices containing average results foridentified groups, thus all persons under 25 undergoing environmentalstress. Alternatively the separate results for individuals may beretained, each matrix being labeled with a group to which it is known tobelong.

The database may be constructed on the basis of any one of numerousmodels to represent dynamic behavior as required. A standard interfaceallows all models to be used together. The dynamic model being used maybe varied and, with it, the meanings of given parameters or theidentities of the actual parameters being used may be varied. Thedifferent models may change the meanings of the different parameters interms of the meanings of correlation of kinetic values to organ ortissue type, or to pathology or to test condition or to patient group.

The individual is imaged in stage 8002. The image is three-dimensionaland typically extends for a finite amount of time. The results arestored in an array of voxels X^. Each voxel stores a range of parametersthat the image was able to measure directly and the parameters mayinclude the behavior of a variable of interest over a period of time,for example, the kinetic or K parameter for passage of a certainradiopharmaceutical (tracer) through a membrane. The imaging processessentially creates a map of tracer uptake and also of dynamic uptakeparameters such as flow of the tracer across given boundaries.

The K parameter may vary, for example, depending on what kind of tissueis being examined, or the pathology present, and so may otherparameters, so that from the behavior of a group of parameters it ispossible to identify the tissue or pathology, provided that one has themathematical tools to compare groups of multi-dimensional dynamicparameters. Referring now to FIG. 108, within a first tissue and/or afirst pathology, two dynamic variables K1 and K2 may covary with a meanover time defined by line 8010 and a standard deviation defined bycircle 8012. Similarly, the same pair of variables may have statisticalbehavior defined by mean 8014 and standard deviation 8016 when locatedwithin a second tissue or a second pathology.

It will be noted that there is a region of overlap between the tworegions, so that unless the behavior of the variable is followed overtime it may not be possible to determine clearly to which tissue type orpathology the current voxel or group of voxels belong. Only by followingthe dynamic behavior do the two cases resolve themselves as belonging toseparate groups.

Returning now to FIG. 107, in stage 8004 a covariance matrix iscalculated and used to provide a measure of the distance between a voxelor a group of voxels or the image results as a whole, and various groupsexisting in the prior data. As well as distance measurement, contextinformation may be used. Thus the system may be constrained not toidentify tissue types that are not relevant to the part of the bodycurrently being imaged. For example an image of the abdominal cavityshould not find brain tissue. An image of bone tissue may be expected tofind the bone itself, as well as gristle, marrow and blood vessels. Animage of muscle tissue may be expected to find blood vessels, nerves andligaments, etc.

Context information may also include information from other types ofimaging, such as CT images, MRI images, ultrasound images, and the like.

Context information may further include known data about the specificpatient such as age, gender, etc. Thus the scan from a patient aged 65or over need only be measured against groups relevant for that patient,and the scans for a pregnant female patient need only be comparedagainst other pregnant female patients.

An image of heart tissue may determine flow parameters and the like andthen the covariance matrix may be used to identify ischemic regions orregions of dead tissue. Dead tissue would probably show up as regions inwhich fluid flow through the membranes is not being regulated at all.

It is noted that the grouping system can be open or closed. In a closedgroup system the existing groups are regarded as the only availablegroups and the patient is assigned to the closest existing group nomatter how unrelated it might be. In an open group system the patient isassigned to the closest group if he is within a certain distancetherefrom but, if he is not within that distance, say further than twostandard deviations from the group, then the patient is regarded asbelonging in a group of his own.

Finally, in stage 8006, an expert system may use decision-making rules,based on the parameters found, in order to advise on a course oftreatment, to make a diagnosis for the patient, or the like. Thus, forexample, a rule may set thresholds of percentages of ischemic or deadtissue within the heart for different treatment regimes.

The expert system may accept data sheets for the tracers(radiopharmaceuticals) or may accept algorithms for scoring and rulesfor analysis, thus, as mentioned above, providing a way of measuring aprobability that a particular set of readings fits a particular tissue,a particular disease, etc. The system may be constrained to check withina limited list of suspected diseases only or within anatomicalconstraints, that is, to take into account the region of the body beingimaged or the known or expected shape or location of organs and thelike. The data compared can be matched with the existing databases overvarious suspected pathologies or conditions. The data may include akinetics value (K), as explained, and the rules may require matching ofhigh level or derived criteria. The platform may match the measuredbehavior to the nearest scenario in the database. Alternatively it maydo something beyond matching the nearest scenario in the database. Forexample, it may check ratios between values, ratios between differentlocations in the body, or ratios between takeup, it may checkaccumulation of different radiopharmaceuticals, among multi-time points,or among different tests, such as tests carried out under stress, rest,etc.

In the following description, a series of suitable parameters will bediscussed, as will a series of environmental variables under whichmeasurements may be made.

Parameters that are directly measurable from the image include kineticflow rates through membranes, hereinafter K values. Also accumulationlevels of a particular tracer in a region may be measured. It will beappreciated that the voxels are of the size range of millimeters whereasindividual cells are much smaller, so the voxel is in any event showingonly macro-behavior in the region. Actual behavior on the cellularlevel, say takeup of sugar in mitochondria, has to be inferred from themeasured parameters.

These values can be measured for one or more different tracers orpharmaceuticals and tend to have a behavior over time. FIGS. 109A . . .109D show behavior of K values for four different radiopharmaceuticalsover time for a given tissue having a given pathology.

FIG. 110A illustrates accumulation of a tracer substance in a scarredtissue, where the membrane is not carrying out regulation. The substancesimply enters and then leaves fairly rapidly and in an unregulatedfashion. FIG. 110B by contrast illustrates accumulation of the tracersubstance in a healthy tissue with an active membrane.

Another parameter that can be considered is glomerular filtration rate.

The parameters can be measured over time and under different conditions.Thus a person being imaged may be placed under physical stress, sensorystress, or the like, or may be exposed to a sensory event over thecourse of the image. Any given test is made under a single condition andthe conditions are added as a label to the test, hereinafter L. Hencenew graphs may be drawn of the behavior of a given parameter over thecourse of a particular event or whilst the patient is under a particularstress.

In the following, X^ represents a matrix resulting from an individualscan. A database X˜ is built of multiple scans taken under differentconditions L, different pathologies j and for different tissues. The aimis that given a scan where one knows two of I, j, and L, one can usedistance measurements against the database to determine the third.

The database X preferably contains groups for all combinations of I, jand L that are of interest.

The initial scan is carried out on the patient in such a way that two ofI, j and L are known, to obtain say X^ I,L.

Now each parameter in the measured scan has a kinetic behavior,including a mean and a standard deviation. Likewise any pair ofparameters can have a covariance that has its own mean and standarddeviation. Any individual measurement can be said to have a distancefrom this behavior measured in standard deviations from the mean. Aseries of measurements over time can be said to have a distance frombehavior which is a summation of distances of the individual points.

This for a single parameter X, the distance may be given byρ⁻¹(X−{circumflex over (X)})

For the entire database, we measure distances{circumflex over (ρ)}_(ikL)( X _(i,j) −{tilde over (X)} _(i,j,j))

Then we find the closest group in the database to the currentmeasurements and assign the missing label.

At this point reference is again made to the point above about open andclosed groups. With a closed group system a definite allocation is madeto the closest group. With an open group system an allocation is onlymade if the new scan is found to be within a predetermined thresholddistance from an existing group from the database, say two standarddeviations or one and a half standard deviations. Otherwise the new scanis assumed to be an independent group.

If the missing parameter is an organ or a tissue then the aboveprocedure can identify which organ or tissue the voxel or group ofvoxels belongs to. If on the other hand the missing parameter is apathology, then the entire scan or the group of voxels can be assigned apathology.

Gatting

Introduction

In myocardial perfusion imaging (MPI), an intravenously administeredradiopharmaceutical is utilized to depict the distribution ofnutritional blood flow in the myocardium. Perfusion imaging identifiesareas in the heart of reduced myocardial blood flow, are associated withischemia or scar. The relative regional distribution of perfusion may beassessed at different levels of activity, such as rest, cardiovascularstress, or both. Imaging can also be performed during acute events, suchas chest pain of unknown etiology, for example, in the coronary careunit or emergency department. Radiopharmaceuticals, which may be usedfor MPI and are approved by the Food and Drug Administration (FDA),include thallium Tl-201, and technetium Tc-99m-labeledradiopharmaceuticals such as sestamibi, tetrofosmin, and Teboroxime, forSPECT imaging and rubidium Rb-82 for PET imaging.

Patients having significant coronary artery narrowing, for example, as aresult of coronary artery disease (CAD), or abnormal coronary flowreserve, will have a zone in the heart muscle of diminishedradiopharmaceutical concentration in the area of decreased perfusion.

While some body organs, such as the kidney, the prostate, or the liver,are relatively static, so as to enable imaging of a period of time thatallows acquiring a statistically significant number of counts, the heartmoves relatively rapidly, at about 80-100 beats per minute, on theaverage, while an average image acquisition may take between 10 and 20minutes. Thus, some manner of correcting for the heart motion isrequired.

Current techniques record data with SPECT and electrocardiogram (ECG),and perform some gating to the data, to incorporate the global andregional atrial and ventricular function and assessment of therelationship of perfusion to regional function.

The Cardiac Electric Cycle:

FIGS. 111A and 111B schematically illustrate a cardiac electrical cycle9020, with appropriate notations, where:

-   -   P wave—the depolarization of the right and left atria;    -   QRS complex—right and left ventricular depolarization, which are        normally activated simultaneously;    -   ST Segment and T wave—ventricular repolarization;    -   U wave—probably, “after depolarizations” in the ventricles;    -   PR interval—time interval from the onset of atrial        depolarization (the P wave) to the onset of ventricular        depolarization (the QRS complex);    -   QRS duration—the duration of ventricular muscle depolarization;    -   QT interval—the duration of ventricular depolarization and        repolarization;    -   RR interval—the duration of ventricular cardiac cycle, which is        an indicator of ventricular rate; and    -   PP interval—the duration of atrial cycle, which is an indicator        of the atrial rate.

Phase 1: Atrial Contraction.

The first phase of the cardiac cycle because it is initiated by theP-wave of the electrocardiogram (ECG), described in greater detailbelow, and represents electrical depolarization of the atria. Atrialdepolarization then causes contraction of the atrial musculature. As theatria contract, the pressure within the atrial chambers increases sothat a pressure gradient is generated across the open atrio-ventricular(AV) valves, thereby causing a rapid flow of blood into the ventricles.Retrograde atrial flow back into the vena cava is impeded by venousreturn (inertial effect) and by the wave of contraction (“milkingeffect”) throughout the atria. However, atrial contraction does producea small increase in venous pressure.

Atrial contraction only accounts for about 10% of left ventricularfilling when a person is at rest because most of the ventricular fillingoccurs before the atria contract and therefore is passive. However, ifheart rate is very high (e.g., during exercise), the atrial contractionmay account for up to 40% of ventricular filling. This is sometimesreferred to as the “atrial kick”. Atrial contribution to ventricularfilling varies inversely with duration of ventricular diastole anddirectly with atrial contractility.

After atrial contraction is complete, the atrial pressure begins to fallcausing a pressure gradient reversal across the AV valves. This causesthe valves to float upward (pre-position) before closure. At this time,the ventricular volumes are maximal, which is termed the end-diastolicvolume (EDV). The left ventricular EDV (LVEDV), which is typically about120 ml, comprises the ventricular preload, defined as the initialstretching of the cardiac myocytes prior to contraction. LVEDV isassociated with end-diastolic pressures of 8-12 mm Hg and 3-6 mm Hg inthe left and right ventricles, respectively.

A heart sound is sometimes noted during atrial contraction. This soundis caused by vibration of the ventricular wall during atrialcontraction. Generally, it is noted when the ventricle compliance isreduced (“stiff” ventricle) as occurs in ventricular hypertrophy (i.e.,increased ventricular mass).

Phase 2: Isovolumetric Contraction:

This phase of the cardiac cycle is initiated by the QRS complex of theECG waveform that represents ventricular depolarization. As theventricles depolarize, excitation-contraction coupling (a process bywhich an action potential triggers a myocyte to contract), leads tomyocyte contraction and the development of ventricular wall tension anda rapid increase in intraventricular pressure. Early in this phase, therate of pressure development becomes maximal.

The abrupt rise in pressure causes the A-V valves to close asintraventricular pressure exceeds atrial pressure. Contraction of thepapillary muscles with attached chordae tendineae prevents the A-V valveleaflets from bulging back into the atria and becoming incompetent(i.e., “leaky”). Closure of the A-V valves results in the First HeartSound. This sound is normally split (˜0.04 sec) because mitral valveclosure precedes tricuspid closure.

During the time period between the closure of the AV valves and theopening of the semilunar valves, ventricular pressure rises rapidlywithout a change in ventricular volume (i.e., no ejection occurs).Contraction, therefore, is said to be “isovolumic” or “isovolumetric.”Individual myocyte contraction, however, is not necessarily isometric.Individual fibers contract isotonically (i.e., concentric, shorteningcontraction), while others contract isometrically (i.e., no change inlength) or eccentrically (i.e., lengthening contraction). Therefore,ventricular chamber geometry changes considerably and the heart becomesmore spheroid in shape; circumference increases and atrial base-to-apexlength decreases.

Phase 3: Rapid Ejection.

When the intraventricular pressures exceed the pressures within theaorta and pulmonary artery, the aortic and pulmonic valves open andblood is ejected out of the ventricles. Blood is ejected because thetotal energy of the blood within the ventricle exceeds the total energyof blood within the aorta. In other words, there is an energy gradientto propel blood into the aorta and pulmonary artery. During this phase,ventricular pressure normally exceeds outflow tract pressure by only afew mm Hg. Although blood flow across the valves is very high, therelatively large valve opening (i.e., low resistance) requires only onfew mm Hg of a pressure gradient to propel flow across the valve.Maximal outflow velocity is reached early in the ejection phase, andmaximal (systolic) aortic and pulmonary artery pressures are achieved.

No heart sounds are ordinarily noted during ejection; the opening ofhealthy valves being silent. The presence of sounds during ejection(i.e. ejection murmurs) indicates valve disease (valve stenosis and/orvalve insufficiency) or intra-cardiac shunts.

Atrial pressure initially decreases as the atrial base is pulleddownward, expanding the atrial chamber. Blood continues to flow into theatria from their respective venous inflow tracts.

Phase 4: Reduced Ejection.

Approximately 150-200 msec after the QRS, ventricular repolarizationoccurs (WKG Waveform T-wave). This causes ventricular active tension todecrease and the rate of ejection (ventricular emptying) to fall.Ventricular pressure falls slightly below outflow tract pressure;however, outward flow still occurs due to kinetic (or inertial) energyof the blood.

Phase 5: Isovolumetric Relaxation.

As the ventricles continue to relax and intraventricular pressure falls,a point is reached when the total energy of blood within the ventriclesis less than the energy of blood in the outflow tracts. When thisoccurs, the pressure reversal causes the aortic and pulmonic valves toabruptly close (aortic precedes pulmonic) causing the Second HeartSound. Valve closure is associated with a small backflow of blood intothe ventricles and a characteristic notch (incisura or dicrotic notch)in the aortic and pulmonary artery pressure tracings. The decline inaortic and pulmonary artery pressures is not as abrupt as in theventricles because of potential energy stored in outflow vessel walls.

Ventricular pressures decrease, but volumes remain constant because allvalves are closed. The volume of blood that remains in a ventricle iscalled the end-systolic volume and is ˜50 ml in the left ventricle. Thedifference between the end-diastolic volume and the end-systolic volumeis 70 ml and represents the stroke volume. Atrial pressures continue torise due to venous return.

Phase 6: Rapid Filling.

When the ventricular pressures fall below atrial pressures, the AVvalves open and ventricular filling begins. The ventricles continue torelax despite the inflow, which causes intraventricular pressure tocontinue to fall by a few additional mm Hg.

The opening of the AV valves causes a rapid fall in atrial pressures anda fall in the jugular pulse. The peak of the jugular pulse just beforethe valve opens is the v-wave.

If the AV valves are healthy, no prominent sounds is heard duringfilling. When a Third Heart Sound is audible, it may represent tensingof chordae tendineae and AV ring during ventricular relaxation andfilling. This heart sound is normal in children, but is oftenpathological in adults.

Phase 7: Reduced Filling.

As the ventricles continue to fill with blood and expand, they becomeless compliant and the intra-ventricular pressure rises. This reducesthe pressure gradient across the AV valves so that the rate of fillingfalls.

Aortic pressure (and pulmonary arterial pressure) continues to fallduring this period.

Electrocardiogram (ECG or EKG)

As the heart undergoes de-polarization and re-polarization, theelectrical currents that are generated spread not only within the heart,but also throughout the body. This electrical activity generated by theheart can be measured by an array of electrodes placed on the bodysurface. The recorded tracing is called an electrocardiogram (ECG).

As noted, FIG. 111B illustrates a typical ECG waveform. The differentwaves that comprise the ECG waveform represent the sequence ofdepolarization and repolarization of the atria and ventricles.

The “P wave” represents the wave of depolarization that spreads from theSA node throughout the atria, and is usually 0.08 to 0.1 seconds (80-100ms) in duration. The brief isoelectric (zero voltage) period after the Pwave represents the time in which the impulse is traveling within the AVnode where the conduction velocity is greatly retarded.

The period of time from the onset of the P wave to the beginning of theQRS complex is termed the “P-R interval”, which normally ranges from0.12 to 0.20 seconds in duration. This interval represents the timebetween the onset of atrial depolarization and the onset of ventriculardepolarization. If the P-R interval is less than 0.2 sec, a conductiondefect (usually within the AV node) is present (first-degree heartblock).

The “QRS complex” represents ventricular depolarization and the durationof the QRS complex is normally 0.06 to 0.1 seconds. This relativelyshort duration indicates that ventricular depolarization normally occursvery rapidly. If the QRS complex is prolonged (longer than 0.1 sec),conduction is impaired within the ventricles. This can occur with bundlebranch blocks or whenever a ventricular foci (abnormal pacemaker site)abnormally become the pacemaker driving the ventricle. Such an ectopicfoci nearly always results in impulses being conducted over slowerpathways within the heart, thereby increasing the time fordepolarization and the duration of the QRS complex.

During the isoelectric period “ST segment” following the QRS, the entireventricle is depolarized and roughly corresponds to the plateau phase ofthe ventricular action potential. The ST segment is important in thediagnosis of ventricular ischemia or hypoxia because under thoseconditions, the ST segment can become either depressed or elevated.

The “T wave” represents ventricular re-polarization and is longer induration than depolarization (i.e., conduction of the re-polarizationwave is slower than the wave of de-polarization).

The “Q-T interval” represents the time for both ventriculardepolarization and re-polarization to occur and therefore roughlyestimates the duration of an average ventricular action potential. Thisinterval can range from 0.2 to 0.4 seconds, depending upon heart rate.At high heart rates, ventricular action potentials shorten in duration,which decreases the Q-T interval. Because prolonged Q-T intervals can bediagnostic for susceptibility to certain types of tachyarrhythmias, itis important to determine if a given Q-T interval is excessively long.In practice, the Q-T interval is expressed as a “corrected Q-T (Q-Tc)”by taking the Q-T interval and dividing it by the square root of the R-Rinterval (interval between ventricular depolarizations). This allows anassessment of the Q-T interval that is independent of heart rate. Normalcorrected Q-Tc intervals are less than 0.44 seconds.

There is no distinctly visible wave representing atrial repolarizationin the ECG because it occurs during ventricular depolarization. Becausethe wave of atrial repolarization is relatively small in amplitude(i.e., has low voltage), it is masked by the much largerventricular-generated QRS complex.

Cardiac Volume and Pressure Changes

FIGS. 114A, 114B and 114C show the cardiac electrical cycle 9020 and thegraduation time scale 9010, superimposed against a typical cardiacvolume and pressure graph 9180 including an aorta pressure tracing 9182,a ventricular volume tracing 9184, an atrial pressure tracing 9186 and aventricular pressure tracing 9188.

As the cycle 9020 passes through the P wave, atrial pressure volume 9184increases.

In the QRS complex, ventricular depolarization occurs and ventricularpressure 9188 increases. Following the T wave, ventricular pressure 9188drops while ventricular volume 9184 increases. The atrial pressure 9186increases briefly at “v” as the blood hits the closed AV valve,following which atrial pressure 9186 rises slowly.

Gated Imaging

Reference in now made to FIG. 112A, which schematically illustrates amethod of radioactive-emission imaging of a heart, in accordance withembodiments of the present invention, comprising:

imaging the heart of a body, for an imaging period greater than at least2 cardiac electrical cycles 9020;

post processing for identifying an average RR interval, based on actualRR intervals 9026, for the body;

post processing for evaluating each specific cardiac electrical cycle,vis-à-vis the average RR interval, and identifying each of the specificcardiac electrical cycles 9020, either as “good,” which is to beincluded in the imaging, or as “bad,” which is to be discarded;

dividing each of the “good” cardiac electrical cycles to timegraduations 9022;

indexing each graduation 9022 with cardiac-cycle indices 9025; and

adding up photon counts that occurred within the graduations of the samecardiac-cycle index 9025.

Additionally, the method may include performing ECG concurrent with theimaging.

Furthermore, the method may include using the ECG input for identifyingdurations of the RR intervals 9026.

Additionally, cardiac electrical cycles deemed associated witharrhythmias are identified as “bad”, during the post processing.

Additionally, the graduations 9022 may be fine graduations, and themethod further includes:

amalgamating the fine graduations 9022 to coarse graduations 9024,wherein each of the coarse graduation 9024 includes at least two finegraduations 9022;

indexing each coarse graduation of each of the dedicated graduation timescales with cardiac-cycle indices 9027; and

adding up photon counts that occurred within the coarse graduations 9024of the same cardiac-cycle index 9027. This is preferably done for aportion of the cardiac cycle, which may be of lesser interest, forexample, the portion between the U-wave and the P-wave.

Reference in now made to FIG. 112B, which schematically illustratesrespiratory gating, in accordance with embodiments of the presentinvention, comprising:

extending the imaging period to cover at least two respiratory cycles9040;

dividing each of the respiratory cycles 9040 to respiratory-cycle stagesand assigning each of the respiratory-cycle stages a respiratory-cycleindex, such as indices 9042 or 9044;

adding up photon counts that occurred within the graduations of commoncardiac-cycle and respiratory-cycle indices, such as cardiac-cycle index9048 and respiratory index 9042, or cardiac-cycle index 9046 andrespiratory index 9044; thereby eliminating respiratory effects.

Additionally, in accordance with an embodiment of the present invention,illustrated in FIG. 116, the method includes:

providing a probe 9100, which comprises a plurality of detecting units9090, or assemblies 9092, each preferably formed as a line of detectingunits 9090, and each having motion providers 9076 and 9078, forproviding motion in a coordinate system 9050, having at least one, andpreferably two degrees of freedom;

wherein for each of the detecting units 9090, time, position and viewingangle are substantially known for every detected photon,

and wherein the imaging the heart further includes imaging by theplurality of detecting units 9090, to provide a 3 dimensional image ofthe heart.

Additionally, the plurality of detecting units 9090 may image the heartin sweeping motions.

Furthermore, the sweeping motions are without pause between minimum andmaximum sweeping angles.

Alternatively, the plurality of detecting units 9090 image the heart instepped motions.

Furthermore, the detecting units 9090 are moved to new viewing positionsat a predetermined stage of the cardiac electrical cycle.

In accordance with embodiments of the present invention, photon countsof each voxel are added, wherein the photon counts occurred within thegraduation of the same cardiac index for all of the detecting units.

Additionally or alternatively, photon counts of each voxel of commoncardiac-cycle and respiratory-cycle indices of a reconstructed image areadded, wherein the photon counts occurred within the graduation of thesame cardiac index for all of the detecting units 9090.

In accordance with embodiments of the present invention, the detectingunits 9090 may sweep in an interlacing manner.

Reference is now made to FIGS. 113A and 113B, which schematicallyillustrate an alternative method of radioactive-emission imaging of aheart, in accordance with embodiments of the present invention,comprising:

imaging the heart for an imaging period greater than at least 2 cardiacelectrical cycles 9020;

providing a graduation time scale 9010, with graduations 9012 and atleast one graduation mark 9016, operative as a point of alignment;

aligning the point of alignment with a specific stage of each of thecardiac electrical cycles, such as “Q,” or “R,” thus, in effectassigning each one of the cardiac electrical cycles 9020 a dedicated oneof the graduation time scales 9010; and

allowing for a discard zone 9015, between adjacent ones of the dedicatedgraduation time scales 9010, where necessary.

Additionally, the method includes performing ECG concurrent with theimaging.

Furthermore, the method includes using the ECG input for the aligning ofthe point of alignment 9016 with the specific stage of each of thecardiac electrical cycles, such as “Q,” or “R.

Additionally, the method includes indexing each graduation 9012 of eachof the dedicated graduation time scales 9010, with cardiac-cycleindices; and

adding up photon counts that occurred within the graduations of the samecardiac-cycle index.

Furthermore, the method includes rejecting photon counts of cardiacelectrical cycles associated with Arrhythmias.

Additionally, as seen in FIG. 113C, the method includes respiratorygating, by:

extending the imaging period to cover at least two respiratory cycles9040;

dividing each of the respiratory cycles to respiratory-cycle stages andassigning each of the respiratory-cycle stages a respiratory-cycleindex, such as the index 9044 or 9042; and

adding up photon counts that occurred within the graduations of commoncardiac-cycle and respiratory-cycle indices, such as the cardiac-cycleindex 9048 and the respiratory cycle index 9042, or the cardiac-cycleindex 9046 and the respiratory cycle index 9044.

Furthermore, as seen in FIGS. 113A and 113B, the graduations 9012 may befine graduations, and the method may includes:

amalgamating the fine graduations 9012 to coarse graduations 9014,wherein each of the coarse graduation 9014 includes at least two finegraduations 9012, for example, in an area between the U-wave and theP-wave, or another area that may be of lesser interest;

indexing each coarse graduation of each of the dedicated graduation timescales 9010 with cardiac-cycle indices 9018; and

adding up photon counts that occurred within the coarse graduations ofthe same cardiac-cycle index 9018.

Additionally, the method includes rejecting photon counts of cardiacelectrical cycles associated with Arrhythmias.

In accordance with still another embodiment of the present invention, amethod of cardiac imaging is provided, which includes:

providing probe 9100, which comprises the plurality of detecting units9090, for which time, position and viewing angle are substantially knownfor every detected photon, as seen in FIG. 116;

imaging the heart for an imaging period which is somewhat greater than asingle cardiac electrical cycle 9020 but which is less than two cardiacelectrical cycles;

dividing the RR interval to graduations 9022 or 9024, as seen in FIG.112A;

indexing each graduation 9022 or 9024 with the cardiac-cycle index 9025or 9027, respectively; and

for each voxel of a reconstructed image, adding up photon counts thatoccurred within the graduations of the same cardiac-cycle index, forthat voxel, from the different detecting units 9090.

FIG. 114A is a graph 9600 of cardiac volume versus pressure over timeand exemplary corresponding volumetric images 9620 in a typical cardiaccycle. Cardiac images 9620 are taken according to graduation time scale9010 in which rapidly increasing cardiac volume 9684 is imaged duringrepeated fine graduations 9012 shown in FIG. 114C. During the cardiaccycle, where minimal volumetric changes occur, during a period of slowlyincreasing cardiac volume, coarse graduations 9014 of FIG. 114C, areoptionally used.

Additionally, graph 9600 shows an almost linear change in volume overtime along a slope 9640, the slope being represented by the formulaΔV/Δt≈dV/dt. Corresponding to slope 9640, image 9670 shows a moderatelydecreased cardiac volume 9620 and a greatly decreased cardiac volume9660.

Calibration

When radiation emitted by radiopharmaceuticals in the body of thesubject propagates through the body it can be attenuated due toabsorption or scattering effects. Any radiological imaging procedure istherefore preceded by a calibration step for in which data are collectedfor calculating attenuation corrections to the radiological image. Thecalibration step involves the transmission of additional radiationthrough the subject so as to estimate the attenuation caused by varioustissues within the target region.

In one technique, a computerize tomography (CT) image of the subject isobtained and the corrections due to attenuation of theradiopharmaceutical radiation are estimated based on the knowledge ofthe internal structure of the subject. This technique is, however,limited from standpoint of cost and availability. Additionally, thespectral lines of the X-ray radiation employed by the CT system arebroader than the spectral lines characterizing radiopharmaceutical. Suchspectra mismatch introduces inaccuracies hence increases the attenuationuncertainties.

In another technique, a radioactive source such as cesium-137 ispositioned in proximity to the subject and allowed to emit radiationtherethrough. The radiological imaging system is then used for detectingthis radiation. The attenuation corrections are calculated from based onthe precise location, emission spectrum and radiation activity of theradioactive source, the operator calibrates of the radiological imagingsystem according to the radiation readings.

It is recognized, however, that the interaction between radiation andmatter such as biological material depends on the spectrum of theradiation. Thus, although the spectral lines of the radioactive sourceis clearer than the spectral lines of X-ray photons, this technique isstill far from being satisfactory because the difference betweenemission spectra of the external radioactive source and theradiopharmaceutical introduces uncertainties to the calculation of theattenuation corrections.

There is thus a widely recognized need for, and it would be highlyadvantageous to have, a method and device for calibrating radiologicalimaging system devoid of the above limitations.

The present embodiments comprise a method and device which can be usedfor radiological imaging. Specifically, the present embodiments can beused to calibrate a radiological imaging system. Particularly, but notexclusively, the present embodiments can be used in radiological imagingsystems which use multi-dimensional data to image non-homogenous targetregions having different tissue types or pathologies, as explained inU.S. Patent Application No. 60/535,830, the contents of which are herebyincorporated by reference.

Referring now to the drawings, FIG. 117 is a flowchart diagram of amethod 5010 for calibrating a radiological imaging system. Theradiological imaging system detects radiation from a target region of asubject having therein at least one radiopharmaceutical characterized byan emission spectrum. Method 5010 begins at step 5011 and continues tostep 5012 in which one or more calibration sources are provided. Thecalibration source can be, for example, one or more radioisotopes havinga relatively short half-life, of the order of a few days, e.g., 10 days,a week or less.

In various exemplary embodiments of the invention the calibrationsources are characterized by the same emission spectrum as the emissionspectrum of the radiopharmaceutical. In various exemplary embodiments ofthe invention the calibration source comprises a radioisotope which isidentical to the radioisotope of the radiopharmaceutical.

The advantage of using identical radioisotopes (hence also identicalemission spectrum) for the radiopharmaceutical and the calibrationsource is that the identical emission spectrum eliminates spectralmismatch errors which may be introduced during the calculations of theattenuation corrections.

The method continues to step 5013 in which the body of the subjectand/or the radiological imaging system is engaged with the calibrationsource. When the calibration source engages the body, it is preferablypositioned in proximity to- and/or within the target region. Thecalibration source can be extracorporeal or extracorporeal calibrationsource. In the former case, the calibration source can be provided in aform of a patch containing a single radioisotope or an arrangement ofradioisotopes. In this embodiment, the calibration source is preferablyattached to an external organ of the subject, being in proximity to thetarget region. When an intracorporeal calibration source is employed,the source can be endoscopically inserted to the subject. This can bedone, for example, by mounting the calibration source on a probe such asa transesophageal or transrectal catheter. The calibration source canalso be encapsulated in a capsule to be taken orally or rectally by thesubject.

When the calibration source engages the radiological imaging system, itis preferably mounted on or within the camera, probe or detector of thesystem. In this embodiment, the calibration source can be providedwithin a container which is transparent to the type of radiation emittedby the source. The container is preferably manufactured sizewise andshapewise compatible with the part of the system which receives it. Forexample, when the calibration source is positioned in the probe of thesystem, the probe can have an opening through which the containerholding the calibration source is inserted into the probe. A devicesuitable for holding the calibration source in the embodiment in whichthe source engages the imaging system is described hereinunder withreference to FIG. 120.

In various exemplary embodiments of the invention the radiation activity(number of disintegrations per unit time) of the calibration source isselected sufficiently high to be detectable by the radiological imagingsystem and sufficiently low so as not to mask radiation emitted by theradiopharmaceuticals present in the subject.

The radiation activity of the calibration source can also be used foridentifying the calibration source. Specifically, the calibration sourcecan be distinguished from the radiopharmaceuticals and/or othercalibration sources (if present), according to its radiation activity.Other identification criteria are also contemplated as further detailedhereinunder.

Preferably, but not obligatorily, the calibration source is adirectional source. In other words, the radiation is emitted by thesource at one or more predetermined directions, with minimal or noradiation in other directions. This can be done, for example, byproviding a calibration source having absorbing or reflecting surfacecovering a portion of the radioisotope's “field-of-view”.

The absorbing or reflecting surface can also be controlled from anexternal location so as to activate and deactivate the calibrationsource as desired. In this embodiment, when the source is inactive, theabsorbing or reflecting surface is closed to prevent radiation frompenetrating the target region.

According to a preferred embodiment of the present invention the methodcontinues to step 5014 in which the calibration source is activated.This can be done by remotely control the absorbing or reflecting surfacesuch that a window is formed in the surface to allow radiation to passtherethrough.

The method continues to step 5015 in which the radiological imagingsystem is used for detecting radiation emitted by the calibrationsource, so as to calibrate the radiological imaging system. Thecalibration can be done by employing an attenuation map, constructedprior to the calibration procedure. The attenuation map includesattenuation information associated with tissue present within targetregion. The attenuation map can be a general map, or, alternatively, aspecific attenuation map can be tailored to each subject or group ofsubjects having similar body structure within the target region.

The attenuation map is typically based on probability distributions forphotons emitted by the calibration source to interact with the tissue inthe target region. Broadly speaking, when a photon interacts with thetissue, it can experience one of the following three processes:absorption (also known as the photoelectric effect), elastic scattering(also known as coherent scattering or Thompson scattering), andinelastic scattering (also known as incoherent scattering or Comptonscattering).

When the photon is absorbed, all of its energy is transferred to thetissue (resulting in emission of free electron) and the attenuation ofthe radiation is manifested as a decrement in the number of photonsarriving at the imaging system. When the photon experiences elasticscattering, its propagation direction can be deflected but its energy ispreserved. In this case, the scattering process is manifested bydetection of photons with the original wavelength at a direction whichis deflected with respect to the emission direction. When the photonexperiences inelastic scattering, a portion of the photon's energy islost during the interaction with the tissue. In this case, thescattering process is manifested by detection of photons with awavelength which is longer than the characteristic wavelength of thesource.

According to a preferred embodiment of the present invention the methodcontinues to step 5016 in which location information of the calibrationsource is received. This embodiment is useful when the location of thecalibration source varies or not known. The location information can beobtained in more than one way.

Hence, in embodiments in which the source is mounted on a mechanicaldevice, such as a catheter or an arm, the location information can beobtained directly from directly from the mechanical device.Alternatively, the calibration source can communicate (mechanically,electrically or via wireless communication) with a position sensingsystem to enable the determination of its location, substantially inreal time.

Knowing the location, radiation activity and emission spectrum of thecalibration source, and given the radiation readings of the radiologicalimaging system (intensity, direction, wavelength, etc.), the attenuationmap can be used for calibrating the imaging system. A mathematicalprocedure for calculating probability distributions is providedhereinafter.

In various exemplary embodiments of the invention the method comprisesan additional step (designated 5017) in which the target region isscanned with the calibration source. The scanning of the region can bedone by displacing the calibration source such that at each position ofthe source the radiation interacts with a different portion of thetarget region. The motion of the calibration source can be establishusing an external mechanism, e.g., an movable arm which can becontrolled manually or automatically. The calibration source can also bea self-propelling source, moving, e.g., in the vasculature either usingan internal propulsion mechanism or via blood flow.

Alternatively or additionally to the motion of the source, the scan ofthe target region can be achieved by controlling the direction at whichradiation is emitted from the calibration source. This can be done byrotating the source or by directly controlling the absorbing orreflecting surface of the source to allow the radiation to propagate atthe desired location.

Once the imaging system is calibrated, the method, optionally andpreferably, continues to step 5018 in which the calibration source isdeactivated. This can be done by remotely controlling the absorbing orreflecting surface so as to close the aforementioned window hence toprevent radiation to enter the target region.

The method ends at step 5019.

Reference is now made to FIG. 118 which is a flowchart diagram of amethod 5050 for calibrating the radiological imaging system, accordingto another aspect of the present invention.

Method 5050 begins at step 5051 and, optionally and preferably,continues to step 5051 in which the concentration of theradiopharmaceutical(s) in a predetermined location or locations of thebody of the subject is obtained. The concentration can be obtainedeither by an appropriate model, which is typically based on the amountof radiopharmaceutical(s) administered to the subject, or by removing asample of a biological material from the predetermined location(s) andmeasuring amount of radiation emitted therefrom. Many predeterminedlocations are contemplated.

One such predetermined location is the vasculature of the subject. Inthis embodiment, the concentration of radiopharmaceutical in the bloodcan be obtained by modeling the vasculature as a reservoir in which theconcentration of the radiopharmaceutical(s) is uniform. Alternatively,the concentration of the radiopharmaceutical(s) can be obtained using amore complex model which takes into account different concentrations ofradiopharmaceutical(s) in the blood in different regions of thevasculature. For example, higher concentrations in regions in whichblood flows into a specific organ (e.g., lungs, liver) and lowerconcentrations in regions in which blood flows out of the specificorgan. Still alternatively, the concentration can be obtained byperforming an ex-vivo measurement of amount of radiation emitted from ablood sample removed from the subject subsequently to the administrationof the radiopharmaceutical(s).

The predetermined location or locations can also comprise other bodyfluids. In various exemplary embodiments of the invention thepredetermined location is the bladder, in which case the concentrationof radiopharmaceutical in the urine can be obtained by modeling or byex-vivo measurement of amount of radiation emitted from a urine sampletaken subsequently to the administration of the radiopharmaceutical(s).

Also contemplated are the feces, in which case the predeterminedlocation can be the bowel, and the concentration can be obtained bymodeling and/or ex-vivo measurement as detailed above.

The predetermined location can also be an organ other than thevasculature, bladder or bowel, provided that the concentration ofradiopharmaceutical(s) in the location is known, e.g., from a model orby ex-vivo measurement, such as, but not limited to, biopsy.

Irrespectively of the source of information from which the predeterminedconcentration(s) of the radiopharmaceutical(s) is known, method 5050proceeds to step 5053 in which radiation being identified as emittedfrom the predetermined location or locations is detected. Method 5050then proceeds to step 5053 in which the detected radiation is used forcalibrating the system. The calibration is based on the location fromwhich the radiation is emitted and the concentration ofradiopharmaceutical present in the location. The operator thus detectsthe radiation and calibrates the radiological system such that theradiation readings (intensity, direction, wavelength) are identified asoriginated from the predetermined location and predeterminedconcentration.

It is recognized that the concentration of the radiopharmaceutical(s)varies with time. Thus, in various exemplary embodiments of theinvention the detection is performed within a sufficiently small timeperiod. The time period depends on the rate of concentration change.Thus, the time period is preferably shorter than the time scale by whichdynamical changes in the concentration occur. For example, when thepredetermined location comprises body fluids or feces, the detection ofthe radiation is preferably performed substantially prior to diffusionof the radiopharmaceutical out of the body fluids or feces. Typical timeperiods include, without limitation, less than a few minutes, morepreferably less than one minute, even more preferably less than 30seconds from the administration of the radiopharmaceutical.

Such short time periods are particularly useful when the predeterminedlocation from which the radiation is emitted is close to the location towhich the radiopharmaceutical(s) is administrated. Thus, for example,when the radiopharmaceutical(s) is administrated intra intravenously,the detection can be done while the vasculature is the only locationfrom which radiation is emitted. In this case any detected radiation isidentified as emitted from the predetermined location and the system canbe calibrated accordingly.

Method 5050 can be executed either as a “stand alone” method or incombination with the method 5010 above, in which case method 5050 servesfor improving the calibration of the system. When method 5050 iscombined with method 5010, selected steps of method 5050 can be executedat any stage of method 5010. For example, selected steps of method 5050(e.g., steps 5052, 5053 and 5054) can be executed prior to steps 5012 or5013 of method 5010. In this embodiment, method 5050 can be used as afirst iteration for the calibration procedure. The operator can thusexecute steps 5052-5054 of method 5050 and then continue to selectedsteps of method 5050 for improving the calibration. Selected steps ofmethod 5050 can also be executed contemporaneously with selected stepsof method 5010.

Reference is now made to FIG. 119 which is a schematic illustration of adevice 5020 for calibrating a radiological imaging system 5022,according to a preferred embodiment of the present invention. Device5020 comprises one or more calibration sources 5024 capable of emittingradiation and being configured to engage the body 5026 of the subject.Calibration source 5024 can include one or more radioisotopes 5025,preferably of short half-life, as further detailed hereinabove.Representative examples of radioisotopes include radioisotopes of achemical element such as, but not limited to, copper, cobalt, gallium,zinc, germanium, yttrium, strontium, technetium, indium, ytterbium,gadolinium, samarium, thallium and iridium.

Any number of calibration sources can be used. In the exemplifiedconfiguration shown in FIG. 119 calibration source 5024 comprises anextracorporeal calibration source 5024 a and an intracorporealcalibration source 5024 b. Intracorporeal calibration source 5024 b canbe encapsulated in a capsule 5028 to be taken orally or rectally by thesubject, or in can be mounted on a probe 5030 such as a transesophagealor transrectal catheter.

As already stated hereinabove, source 5024 is preferably characterizedby the same emission spectrum as the radiopharmaceutical(s) present inthe subject. The number of radioisotopes employed by device 5020, eitherwithin a single calibration source or within different calibrationsources, preferably equals the number of radiopharmaceuticals present inthe subject. Thus, according to the presently preferred embodiment ofthe invention each radioisotope of device 5020 is preferablycharacterized by an emission spectrum of a respectiveradiopharmaceutical.

Additionally, the radiation activity of source 5024 is selectedsufficiently high to be detectable by the radiological imaging systemand sufficiently low so as not to mask radiation emitted by theradiopharmaceuticals present in the subject.

Source 5024 preferably comprises a communication unit 5034 for allowingsource 5024 to communicate with a remote unit 5036 as further detailedhereinunder. The communication can be wired communication or, morepreferably, wireless communication, such as, but not limited to,radiofrequency or infrared communication.

The ability to accurately calibrate system 5022 depends inter alia onthe identification of source(s) 5024, including its location such thatthe radiation detected by system 5022 can be traced back to the emittingsource. There are several identification criteria which arecontemplated.

Hence, in one embodiment, the radioisotopes of source 5024 are arrangedgridwise over a grid, such that each radioisotope is characterized by adifferent emission spectrum and a different coordinate of grid. Theidentification in this embodiment is therefore by mapping emissionspectrum to a coordinate on the grid.

In another embodiment, different radioisotopes have different radiationactivity so as to allow their identification according to the intensityof the radiation arriving at system 5022.

In still another embodiment, each calibration source is characterized bya distinguishable geometrical shape. The geometrical shape can be ashape of the patch containing the radioisotopes. The geometrical shapecan also be a barcode formed, for example, by a specific arrangement ofthe radioisotopes within the patch. Thus, in this embodiment theidentification of source 5024 is by the shape of the image generated bysystem 5022.

In yet another embodiment, the calibration sources are identified byspecific identification codes. In this embodiment each source isassociated with a unique identification code which can be transmitted bysource 5024, e.g., via communication unit 5034.

As stated, a remote activation and deactivated of source 5024 can beobtained using an absorbing or reflecting surface 5030. Surface 5030 canbe manufactured with a window 5032 which can be opened and closed byremote activation via communication unit 5034.

Source 5024 is preferably capable of moving to allow source 5024 to scantarget region 5027. The motion can be translational motion or rotationalmotion and can be established manually or automatically as furtherexplained above. According to a preferred embodiment of the presentinvention source 5024 is associated with a motion mechanism 5038 whichcan be a movable arm 5040 or a propulsion mechanism 5042. When source5024 is self-propelled, motion signals can be transmitted thereto viaunit 5034.

Unit 5034 can also be used for establishing communication between source5024 and a position sensing unit 5044 so as to allow the determinationof the location of source 5024 as further detailed hereinabove.

Reference is now made to FIG. 120, which is a schematic illustration ofa radiological imaging system 5060 and an administration device 5062,according to a preferred embodiment of the present invention. Device5062 can be used to administer one or more radiopharmaceuticals duringor prior to a radiological imaging procedure.

Device 5062 comprises a device body 5064 configured for holding theradiopharmaceutical(s) therein. The device body can be a disposable. Inthe exemplified embodiment of FIG. 120 device 5062 is manufactured as asyringe, but this need not necessarily be the case, since, for someapplications, it may not be necessary for the device to function as asyringe. For example, in various exemplary embodiments of the inventiondevice 5064 may serve as an intravenous bag of an intravenous accesskit.

Device body 5064 is in fluid communication with an outlet conduit 5066.During administration, the radiopharmaceutical, which is typicallyprovided in a liquid form, is extruded from body 5064 through conduit5066. Conduit 5066 can be flexible or rigid as desired. For example, inone embodiment conduit 5066 is a needle which can be introduced into thelumen of a blood vessel of the subject, and in another embodimentconduit 5066 is a flexible tube configured to be connected to an inletconduit (not shown), such as a hub or a cannula on the subject's body.

Device body 5062 has a detachable part 5068 holding a calibration sourcewhich can be any of the aforementioned calibration sources. For example,the calibration source can be identical to the radiopharmaceutical beingadministrated into the subject. Detachable part 5068 can be connected toany location on device body 5064. In the representative example shown inFIG. 120 part 5068 covers outlet conduit 5066. Thus, part 5068 can alsoserve as a cap to body 5064. Alternatively, part 5068 can be connectedto the side of device body 5064 without covering conduit 5066.

In any event, the interface 5070 between body 5064 and detachable part5068 is designed and constructed to avoid leakage of theradiopharmaceutical or the calibration source while part 5068 isdetached from body 5064. This can be achieved by anyway known in theart, include, without limitation, a valve, a double partition and thelike.

The detachment of part 5068 from body 5064 can be done in a reversibleor non-reversible manner. When the detachment is in a reversible manner,interface 5070 comprises a connector 5072 which can connect anddisconnect the two parts. When the detachment is in a non-reversiblemanner, interface 5070 is designed such that the user breaks interface5070, e.g., by twisting or bending body 5064, to detach part 5068.

Once detached, part 5068 can be mounted on a mounting location 5074 ofsystem 5060, such that radiation emitted from the calibration source isdetected by system 5060. According to a preferred embodiment of thepresent invention part 5068 is sizewise and shapewise compatible withmounting location 5074, so as to allow system 5060 to receive part 5068.The radiation emitted from the calibration source can then by utilizedto calibrate system 5060 as further detailed hereinabove.

Compton Mapping

The present embodiments comprise a radiological imaging system andmethod for providing a three-dimensional anatomical image.

Studies which produce three-dimensional images are known in the art andinclude single photon emission computerized tomography (SPECT) andpositron emission tomography (PET).

SPECT or PET cameras include one or more two-dimensional detectors whichrotate around the biological body and detect radiation emitted from theradiopharmaceuticals as projection data. Data processing means performreconstruction of multiple-slice images of radiopharmaceuticaldistribution in the body through the convolution and back-projection ofthe projection data. The images of the temporal and spatialdistributions of the radiopharmaceuticals are reconstructed by usingmathematical imagery construction techniques similar to those applied inCT. SPECT and PET provide unique functional information on blood flowand metabolism not easily obtainable by other technologies.

SPECT and PET differ both in the detection hardware and in theradiopharmaceuticals used. The detection hardware for SPECT and PETsystems is different in terms of the manner in which the systems detectand record events and is also different because PET systems operate athigher count rates over SPECT systems.

The radiopharmaceuticals differ in terms of half-lives and energylevels. PET involves the detection of gamma rays in the form ofannihilation photons from positron emitting radiopharmaceuticals, whichtypically include radioisotopes having short half-lives of less than afew hours. SPECT, on the other hand, uses longer-lived isotopes withhalf-lives of several hours to several tens of hours. Examples ofradiopharmaceutical suitable for PET cameras include, ¹⁸F (half-life ofapproximately 110 minutes), ¹¹C (approximately 20 minutes), ¹³N(approximately 10 minutes) and ¹⁵O (approximately 2 minutes). Examplesof radiopharmaceutical suitable for SPECT cameras include, ⁹⁹Tc (halflife of approximately 6 hours) and ²⁰¹Tl (approximately 74 hours).

As the radiopharmaceuticals employed by prior art radiological imagingare designed to mark specific sites within the region of interest, priorart radiological imaging techniques are suitable mainly for diagnosingtumors, infection and other disorders which are detected by evaluatingthe function of organs, such as the kidney, heart, lungs, gallbladder,bowel, thyroid and the like.

Radiological imaging, however, is a less favored technique forconstructing three-dimensional anatomical images. Most presentlyavailable three-dimensional anatomical imaging techniques are based onmagnetic resonance, X-ray or ultrasound.

There is thus a widely recognized need for, and it would be highlyadvantageous to have a radiological imaging system and method forproviding a three-dimensional anatomical image.

The present embodiments can be used to provide anatomicalthree-dimensional image via with SPECT or PET cameras.

Referring now to the drawings, FIGS. 121 a-e are schematic illustrationsof a system 5120 for generating a three-dimensional image of a targetregion 5127 of a subject 5121. In its simplest configuration, system5120 comprises one or more radioactive sources 5124, configured toengage body 5126 of subject 5121. Source 5124 can be an extracorporealsource, as shown in FIG. 121 a, an intracorporeal source, as shown inFIGS. 121 c-e, or a combination of one or more intracorporeal sourcesand one or more extracorporeal sources, as shown in FIG. 121 b. Oneskilled in the art will recognize that several components of system 5120have been omitted from FIGS. 121 b-c for clarity of presentation.

Any number of radioactive sources can be used, where each radioactivesource can independently comprise one or more radioisotopes 5129 havinga relatively short half-life, of the order of a few days, e.g., 10 days,a week or less.

System 5120 further comprises a radiological imaging camera 5122, fordetecting from target region 5127 radiation emitted by source 5124 toprovide radiation data. Camera 5122 can be any type of radiologicalimaging camera, including, without limitation, a SPECT camera and a PETcamera. System 5120 further comprises an analyzer 5123, for receivingand analyzing the radiation data from camera 5122. Analyzer 5123 usesthe radiation data and constructs a three-dimensional image of targetregion 5127.

Many methods for constructing the image are contemplated.

In one embodiment, analyzer 5123 determines the attenuation propertiesof the tissue and uses these properties to construct anatomicalthree-dimensional image of the target region. In another embodiment, theimage is constructed by computerized tomography, in which caseabsorption data are processed using a mathematical procedure, such asRadon transform or exponential projection. In an additional embodiment,the image can be constructed by inverse scattering, in which casescattering data are treated as a mathematical inverse problem which isthen solved numerically, for example, using a set of linear integralequations in which time appears only implicitly. The image can also beconstructed by a combination of methods, for example, a combination ofcomputerized tomography and inverse scattering, in which case bothabsorption and scattering data are used.

According to a preferred embodiment of the present invention analyzer5123 uses the radiation information for constructing an attenuation map,which can includes attenuation information associated with tissuepresent within target region.

System 5120 can be used either for obtaining a three-dimensional imageper se, or in combination with more complex diagnostic procedures, suchas, but not limited to, radiological imaging. It is recognized that theknowledge of body contours during radiological imaging allows thephysician or operator to accurately position the camera. In conventionalradiological imaging, an X-ray CT scan is performed prior to theradiological imaging procedure so as to determine the body contours ofthe subject. Subsequently, the radiological imaging camera is positionedabout an inch above the subject highest point.

However, as the X-ray CT images and radiological images are captured atdifferent times, the correlation between the images is oftentimeserroneous due to subject motions. In particular, although the X-ray CTimages can accurately provide information regarding the internalstructure of the subject, this information is not useful, e.g., forcalculating attenuation corrections to the radiological images, due tothe non-overlapping times at which the X-ray CT and radiological imagesare taken.

In contrast, system 5120 can be used to obtain, substantiallysimultaneously (e.g., within a few seconds), both a three-dimensionalanatomical image and a (preprocessed) radiological image. Being takensubstantially simultaneously, the information collected from thethree-dimensional anatomical image can be used for the calculation ofthe attenuation corrections. The preprocessed radiological image canthen be processed using the calculated attenuation corrections. Thecalculation of attenuation corrections from the information collected bysystem 5120 is particularly useful in situations in which the bodycontours includes complex morphology such as, for example, non-convexmorphology (armpit, breast, etc.). In such situations, the numericalerror of the preprocessed radiological image can be considerable, andthe attenuation corrections can significantly improve the quality of theimage.

According to a preferred embodiment of the present invention theradiation activity (number of disintegrations per unit time) of theradioactive sources is selected sufficiently high to be detectable bythe radiological imaging system. In the embodiments in which system 5120is used in combination with radiological imaging, the radiation activityis selected sufficiently low so as not to mask radiation emitted by theradiopharmaceuticals present in the subject.

The radiation activity of radioactive source 5124 can also be used foridentifying source 5124. Specifically, source 5124 can be distinguishedfrom the radiopharmaceuticals and/or other radioactive sources (ifpresent), according to its radiation activity. Other identificationcriteria are also contemplated as further detailed herein.

In the embodiments in which system 5120 is used in combination withradiological imaging, source 5124 is preferably characterized by thesame emission spectrum as the radiopharmaceutical(s) present in thesubject. The number of radioisotopes employed by system 5120, eitherwithin a single radioactive source or within different radioactivesources, preferably equals the number of radiopharmaceuticals present inthe subject. Thus, according to the presently preferred embodiment ofthe invention each radioisotope is preferably characterized by anemission spectrum of a respective radiopharmaceutical.

Source 5124 preferably comprises a communication unit 5134 for allowingsource 5124 to communicate with a remote unit 5136 as further detailedhereinunder. The communication can be wired communication or, morepreferably, wireless communication, such as, but not limited to,radiofrequency or infrared communication.

Preferably, but not obligatorily, source 5124 is a directional source.In other words, the radiation is emitted by the source at one or morepredetermined directions, with minimal or no radiation in otherdirections. This can be done, for example, by providing a radioactivesource having absorbing or reflecting surface 5130 covering a portion ofthe radioisotope's “field-of-view”.

Surface 5130 can also be controlled from an external location so as toactivate and deactivate the radioactive source as desired. In thisembodiment, when the source is inactive, the absorbing or reflectingsurface is closed to prevent radiation from penetrating the targetregion. For example, surface 5130 can be manufactured with a window 5132which can be opened and closed by remote activation via communicationunit 5134.

Source 5124 is preferably capable of moving to allow source 5124 to scantarget region 5127. The motion can be translational motion or rotationalmotion and can be established manually or automatically as furtherexplained above. According to a preferred embodiment of the presentinvention source 5124 is associated with a motion mechanism 5138 whichcan be a movable arm 5140 or a propulsion mechanism 5142. When source5124 is self-propelled, motion signals can be transmitted thereto viaunit 5134.

Unit 5134 can also be used for establishing communication between source5124 and a position sensing unit 5144 so as to allow the determinationof the location of source 5124.

The use of a plurality of radioactive sources at known locations forconstructing a three-dimensional image has many advantages.

First, in conventional anatomical imaging (e.g., X-ray CT), it isoftentimes required to acquire more than one image at different bodypositions (and different times) and to combine the image at a laterstage. For example, when the imaging is of the cardiac muscle, one setof images is acquired when the subject is in supine position and anotherset of images is acquired when the subject is in prone position such asto image the cardiac muscle from both sides. This technique, however,requires image registration.

The use of a plurality of radioactive sources at known locations, inaccordance with the present embodiments, successfully overcomes thisproblem. The known locations provide registration capabilities and thereis no need to change the body position. Furthermore, the use of source5124 facilitates the registration of rest versus stress tests.

Second, in conventional anatomical imaging, it is required to performmotion correction, to account for volitional or non-volitional motion(e.g., breathing) of the subject. Traditionally in X-ray CT, thephysician visually examines each projection (raw image) to determinewhether the projection was taken while the subject was moving orsignificantly displaced. Such projections are considered corrupted andare either corrected using an image correction algorithm or excludedfrom the image reconstruction. In severe cases (e.g., when there aremany corrupted) the entire imaging process is repeated.

The use of a plurality of radioactive sources at known location, inaccordance with the present embodiments, can significantly improve themotion correction because the motions of the subject can be monitored,substantially in real time, by determining changes in the locations ofthe radioactive sources.

An additional advantage of the present embodiments is that source 5124can also be used as a calibration source for camera 5122, as furtherdetailed herein.

As stated, source 5124 can be an extracorporeal or an intracorporealsource. In the former case, the source can be provided in a form of apatch 5125 containing a single radioisotope or an arrangement ofradioisotopes. In this embodiment, the source is preferably attached toan external organ of the subject, being in proximity to the targetregion. When an intracorporeal source is employed, the source can beendoscopically inserted to the subject. This can be done, for example,by mounting the source on a probe 5130 such as a transesophageal ortransrectal catheter. The source can also be encapsulated in a capsule5128 to be taken orally or rectally by the subject.

FIG. 121 c is a schematic illustration of an embodiment in which theintracorporeal source is used for imaging the stomach. Shown in FIG. 121c is the esophagus 5360 and the stomach 5361. Also shown are theintracorporeal source 24, which is inserted through esophagus 5360 by acatheter 5363 and positioned in stomach 5361. Camera 5122 is positionedexternally on the upper abdomen 5365, opposite to source 5124. Inoperation mode, radiation is transmitted through the stomach to providean image thereof as further detailed above. This embodiment can be usedfor imaging benign tumors such as Leomyoma, or malignant tumors such ascarcinoma or lymphoma.

The ability to insert the intracorporeal radioactive source through theesophagus allows the operator to obtain images of the esophagus itself,thereby to locate pathologies, such as the carcinoma of the esophagus,thereon. In this embodiment, both the source and the camera arepositioned such that the radiation is transmitted through the gapbetween two ribs.

Reference is now made to FIG. 121 d, which is a schematic illustrationof an embodiment in which the intracorporeal radioactive source is usedfor imaging the prostate or bladder. Shown in FIG. 121 d are the rectum5367, the bladder 5366, the prostate 5370 and the urethra 5369. In thepresent embodiments, intracorporeal radioactive source 5124 can beinserted through the anus 5368 into the rectum 5367, or through theurethra 5369. When source 5124 is inserted through the urethra it can beused for imaging the prostate, in which case source 5124 is positionednear the prostate, or the bladder, in which case source 5124 is insertedinto the bladder as shown in FIG. 121 d. Camera 5122 can then bepositioned on the lower external abdomen, and a three-dimensional imageof the prostate or the bladder can be obtained.

Reference is now made to FIG. 121 e, which is a schematic illustrationof an embodiment in which the intracorporeal radioactive source is usedfor imaging the uterus, bladder or ovary. Shown in FIG. 121 e are therectum 5367, the bladder 5366, the uterus 5372 and the ovary 5373. Inthe present embodiments, source 5124 can be inserted through the vagina5374. Source 5124 can be mounted on a catheter and can be inserted intothe uterus. Camera 5122 can then be positioned on the mid externalabdomen, and a three-dimensional image of the uterus, bladder or ovarycan be obtained. This embodiment can be used for locating or diagnosingpolyps in the uterus or bladder. Additionally this embodiment can beused for locating or diagnosing benign tumors in the uterus (e.g.,myomas) or any malignant tumors therein. For the ovary, this embodimentcan be used for imaging any primary or secondary malignant tumorstherein.

Following is a description of imaging methods according to variousaspects of the present invention. It is to be understood that, unlessotherwise defined, the method steps described hereinbelow can beexecuted either contemporaneously or sequentially in many combinationsor orders of execution. Specifically, the ordering of the flowcharts ofFIGS. 122 and 123 below is not to be considered as limiting. Forexample, two or more method steps, appearing in the followingdescription or in a corresponding flowchart in a particular order, canbe executed in a different order (e.g., a reverse order) orsubstantially contemporaneously.

Reference is now made to FIG. 122 which is a flowchart diagram of amethod 5150 for constructing a three-dimensional image of a targetregion of a subject, according to various exemplary embodiments of thepresent invention.

Method 5150 begins at step 5151 and continues to step 5152 in which thetarget region is engaged by one or more extracorporeal and/orintracorporeal radioactive sources, which can be in a form of a patch, acapsule or it can be mounted on an endoscopic device as further detailedhereinabove. Depending on the type of the source, the engagement of thetarget region can be done by attaching the source to an external organof the subject (when the source is an extracorporeal patch), byendoscopically inserting the source to the subject (when the source ismounted on an endoscopic device), or by administering the source to thesubject either orally or rectally (when the source is in a form of acapsule).

According to a preferred embodiment of the present invention method 5150continues to step 5153 in which the source is activated. This can bedone by remotely control the absorbing or reflecting surface such that awindow is formed in the surface to allow radiation to pass therethrough.The method continues to step 5154 in which radiation data correspondingto radiation emitted by the radioactive source is received from thetarget region. The radiation data can be received by a radiologicalimaging camera.

According to a preferred embodiment of the present invention the methodcontinues to step 5155 in which location information of the source isreceived. This embodiment is useful when the location of the sourcevaries or not known. The location information can be obtained in morethan one way.

Hence, in embodiments in which the source is mounted on a mechanicaldevice, such as a catheter or an arm, the location information can beobtained directly from the mechanical device. Alternatively, thecalibration source can communicate (mechanically, electrically or viawireless communication) with a position sensing system to enable thedetermination of its location, substantially in real time.

According to a preferred embodiment of the present invention method 5150continues to step 5156 in which the radiological imaging camera iscalibrated. The calibration is preferably done using the radioactivesource which, in the present embodiments also serves as a calibrationsource.

The calibration can be done by employing an attenuation map, constructedprior to the calibration procedure. The attenuation map includesattenuation information associated with tissue present within targetregion. The attenuation map can be a general map, or, alternatively, aspecific attenuation map can be tailored to each subject or group ofsubjects having similar body structure within the target region. Thus,knowing the location, radiation activity and emission spectrum of thecalibration source, and given the radiation readings of the radiologicalimaging camera (intensity, direction, wavelength, etc.), the attenuationmap can be used for calibrating the camera. A mathematical procedure forcalculating probability distributions is provided hereinafter.

In various exemplary embodiments of the invention the method comprisesan additional step (designated 5157) in which the target region isscanned with the source. The scanning of the region can be done bydisplacing the source such that at each position of the source theradiation interacts with a different portion of the target region. Themotion of the source can be establish using an external mechanism, e.g.,a movable arm which can be controlled manually or automatically. Thesource can also be a self-propelling source, moving, e.g., in thevasculature either using an internal propulsion mechanism or via bloodflow.

Alternatively or additionally to the motion of the source, the scan ofthe target region can be achieved by controlling the direction at whichradiation is emitted from the source. This can be done by rotating thesource or by directly controlling the absorbing or reflecting surface ofthe source to allow the radiation to propagate at the desired location.

Method 5150 continues to step 5158 in which the radiation data isanalyzed so as to construct the three-dimensional image of the targetregion, as further detailed hereinabove.

Once the three-dimensional image is constructed, the method, optionallyand preferably, continues to step 5159 in which the source isdeactivated. This can be done by remotely controlling the absorbing orreflecting surface so as to close the aforementioned window hence toprevent radiation to enter the target region.

The method ends at step 5160.

As stated, the three-dimensional image can be constructed as a part of aradiological imaging procedure.

Reference is now made to FIG. 123 which is a flowchart diagram of amethod 5170 for constructing a radiological image of a target region,according to various exemplary embodiments of the invention. Method 5170begins at step 5171 and continues to step 5172 in which athree-dimensional image of the region is provided, for example, byexecuting selected steps of method 5150. Method 5170 continues to step5173 in which a preprocessed radiological image of the target region isprovided. Step 5173 can be performed by any radiological imagingprocedure known in the art. Typically, the procedure includes theadministration of radiopharmaceuticals to the subject and the detectionof radiation data from the radiopharmaceuticals using a radiologicalimaging camera. According to a preferred embodiment of the presentinvention the same radiological imaging camera is used for thethree-dimensional image (step 5172) and the preprocessed radiologicalimage (step 5173).

Method 5170 continues to step 5174 in which attenuation corrections tothe preprocessed radiological image are calculated. The attenuationcorrections are based on the three-dimensional image and preferablyinclude probability distribution for photons to interact (via absorptionor scattering) with tissue in the as viewed in the three-dimensionalimage of the target region. The attenuation corrections can be providedin a form of, e.g., an attenuation map, representing the contribution ofdifferent sectors of the target region to the attenuation of radiation.Method 5170 then continues to step 5175 in which the (preprocessed)radiological image is processed. The processing preferably includes thecorrection of the preprocessed image in accordance with the attenuationcorrections (or attenuation map) to thereby provide a radiologicalimage.

The method ends at step 5176.

Reference is now made to FIG. 124 which is a flowchart diagram of amethod 5200 for calculating intensity attenuation of a radiologicalimage, according to various exemplary embodiments of the presentinvention.

The method begins at step 5201 and continues to step 5202 in which anattenuation map is provided. The attenuation map can be obtained in anyway known in the art. For example, in one embodiment, the attenuationmap is obtained using computerized tomography (CT) image or a magneticresonance image (MRI) of the target region. Given an MRI or CT image,the attenuation map is constructed from the image by extractinginformation on the types and shape of tissues present in the targetregion (e.g., bones, lungs) and utilizing this information forcalculating the attenuation associated with each tissue type.

In another embodiment, the attenuation map can be obtained byconstructing a model of the target region. In the simplest case, themodel comprises at least one geometrical shape representing water bulk.Thus, in this embodiment, the body is modeled as a water bulk (of aspecific shape), whereby all the attenuations are calculated assumingthe photons interact with water. This model can be improved byconsidering, in addition to the interaction with water, the passage ofphotons through the air gap between the detector of the radiologicalimaging system and the body. The distance between the detector(s) andthe body can be calculated (e.g., knowing the size of the imaging systemand the approximate shape of the body) or measured.

In an additional embodiment, the attenuation map can be obtained usingone or more radioisotopes which can be present within the target region,in proximity thereto or outside the body. For example, in variousexemplary embodiments of the invention the aforementioned calibrationsource is used for constructing the attenuation map, as further detailedhereinabove. Alternatively or additionally, one or more non-specificradioisotopes can be administered to the subject, e.g., into thevasculature. Readings of emissions from the administered radioisotope(s)can then be used for constructing attenuation map, as further detailedin the Examples section that follow.

In still another embodiment, the attenuation map can be obtained fromthe radiological image per se. In this embodiment, a mathematicalalgorithm determines the contribution for each voxel of the radiologicalimage to the attenuation. For example, the algorithm can classify thevoxels into different groups (water, bone, air, etc.) whereby each groupis associated with different attenuation. The classification can be doneby correlating intensity levels of the voxels with their type, or byinputting information from other resources.

Two or more of the above embodiments can also be combined so as toimprove the quality of the attenuation map.

Once the attenuation map is obtained, the method proceeds to step 5203in which the attenuation map is utilized for calculating probabilitydistributions for photons emitted by the radiopharmaceutical(s) tointeract with the tissue. As stated, the probability distributions cancomprise probabilities of photons to be absorbed by or scattered off thetissue. Knowing the interaction probability of the photons at eachvoxel, the intensity attenuation of the radiological image can becalculated.

The above process can be performed for one or more energy bins. Asstated, when the photon is scattered off matter (tissue, water moleculeetc.) via Compton scattering some of its energy is lost. Thus, even whenthe emission spectrum of the radiopharmaceutical is narrow, there ismore than one possible energy level at which the emitted photons can bedetected. The number of possible energy level is further increased whenthere is more than one radiopharmaceutical. For a plurality ofradiopharmaceuticals and a plurality of energy levels, the methodassociates to each voxel a local probability which describes (inprobabilistic manner) whether photons emitted by each of theradiopharmaceuticals are absorbed, scattered coherently or scatteredincoherently. In case of coherent or incoherent scattering, the methodcan also calculate the propagation direction and energy of the photonafter the interaction.

The local probabilities associated with each voxel in the image form anabsorption-scattering map of the target region in a sense that for eachelementary portion of the voxel, the outgoing photon has a known (again,probabilistically) energy and propagation direction. Thus, when adetector, tuned to a specific energy bin and positioned at a knownlocation with respect to the target region, detects a photon, the methodcan calculate the location in the target region from which the photonwas emitted. A plurality of detectors (or a single detector scanning aplurality of location) can thus be employed at a plurality ofpredetermined energy bins and the spatial distribution of eachradiopharmaceutical can calculated at each energy bin, therebyincreasing the amount of information which can be extracted from thetarget region.

The method ends at step 5204.

The following example relates to the issue of reconstructing intensitydistributions.

An intensity distribution I, conventionally defined in terms ofradioactive emissions per seconds, is now redefined as a vector ofdistributions over the volume U, forming the input space. Each dimensionof the vector corresponds to a different radioisotope. The universal setU comprises a set of basic elements u (e.g., pixels in two dimensionalspaces, voxels in three dimensional spaces), and I(u) is the intensityin a given basic element uεU. For j radioisotopes this becomesI(u)^((j,t)). An inverse (or reconstruction) problem arises when onecannot sample directly from I, but can sample from a given set of viewsΦ. A projection φεΦ is defined by the set of probabilities {φ(u): uεU},where φ(u) is the probability of detecting a radioactive emission from avoxel u, as defined by viewing parameters, such as the physical andgeometrical properties of the detecting unit, as well as the attenuationparameters of the viewed volume U, and the time parameters. Ameasurement is obtained by choosing a view φεΦ, and then samplingaccording to the viewing parameters.

For j radioisotopes or markers and k detectors, the probability ofseeing a particle becomes Φ_(j) ^(k)(u)

In the following analysis, I is the intensity of a radioactivesubstance, and the viewing parameters include the geometrical propertiesof a collimated detecting unit and the detecting unit's position andorientation with respect to volume U. The number of radioactiveemissions counted by the detecting unit within a time interval is aPoisson distribution, where φ(u) is the detection probability of aphoton emitted from voxel uεU and the mean of the distribution is theweighted sum Σ_(uεU)φ(u)I(u).

For the case of the kth detector a measurement Y_(k)=Σ_(uεU)X_(t)(u),where X(U) is a Poisson distribution.X _((j,k,t))(u)=I ^((i,t))(u)·φ(u)_(j) ^(k)(u),  (1)where,Y _((j,k,t)) =ΣX _((j,k,t))(u).  (2)Hence:Y(_((j,k,t)))=Poisson(Y _((j,k,t))).  (3)

The projection set is thus defined by a matrix Φ, whose rows are theprojections of the chosen views. I is a vector of densities (specifiedper each element in U), and ΦI is a vector of respective effectiveintensity levels for the views in the set. A vector of measurements y isobtained by a random sample from each view (according to the associatedPoisson distribution). There are various known reconstruction methodsthat provide estimators for I given the projections Φ and themeasurements y.

Signal Isolation

-   -   Detector t, I^(i)(u) The intensity density of isotope i in voxel        u is denoted by photons at energy bin b. A detector is referred        to a as a composite of a y_(tb) detects collimator and a        radiation sensor such as CZT, placed at some location. In an        actual system, a physical detector that takes snap shots from        several locations is regarded as different detectors for the        purpose of the following derivations. The probability of a        photon emitted from isotope i in voxel u, to be detected by        detector t at energy bin b, is    -   This probability can be determined by the geometrical and        physical φ_(tb) ^(i)(u) denoted by properties of the detector,        its position, orientation, and the reduction of the energy of        the photon emitted from isotope I, to the measured energy b. In        the following derivations will be referred to as a functional,        which can be calculated analytically, e.g., using φ_(tb) ^(i)(u)        geometrical considerations combined with the experimentally        measured scattering effects. Alternatively the functional can be        calculated only in part with further tuning via experiment.    -   The change of angle θ of a photon emitted at energy E₀, and        scattered to energy E is given by:

$\begin{matrix}{{{E\left( {E_{\; 0},\theta} \right)} = {\left. {E_{\; 0}\left\lbrack \frac{\mspace{11mu}{m_{\; e}\mspace{11mu} c^{\; 2}}}{\mspace{11mu}{{m_{\; e}\mspace{11mu} c^{\; 2}} + {E_{\; 0}\;\left( {1 - {\cos\;(\theta)}} \right)}}} \right\rbrack}\Leftrightarrow{\cos(\theta)} \right. = {1 - {\left( {\frac{1}{\; E} - \frac{1}{\mspace{11mu} E_{\; 0}}} \right)m_{\; e}c^{\; 2}}}}},} & \left( {4(} \right.\end{matrix}$Where m_(e) represents the rest mass of the electron, and c is the speedof light in a vacuum. of photons that are emitted from voxel u anddetected X_(tb) ^(i)(u) The random count in measurement tb (detector tat energy bin b), is modeled by a Poisson process with

The total count of photons detected in measurement tb is Σ_(i)φ_(tb)^(i)(u)I^(i)(u) mean from the I^(i)(u), and the problem is toreconstruct the intensities Y_(tb)=Σ_(u)X_(tb)(u)·y_(tb) measurements

Simultaneous Submission of Multiple Isotopes

-   -   The measurements have a Poisson distribution        ·Y _(tb)˜Poiss(Σ_(i)Σ_(u)φ_(tb) ^(i)(u)I ^(i)(u))  (5(    -   The log-likelihood is given by:

$\begin{matrix}{\;{{L\left( {{y❘I^{1}},I^{2},K} \right)} = {{\sum\limits_{tb}{\ln\;{{Poiss}\left( {y_{tb}❘{\sum\limits_{i}{\sum\limits_{u}\;{{\phi_{tb}^{i}(u)}{I^{i}(u)}}}}} \right)}}} = {\sum\limits_{tb}\left\{ {{- {\sum\limits_{i}{\sum\limits_{u}\;{{\phi_{tb}^{i}(u)}{I^{i}(u)}}}}} + {y_{tb}\mspace{11mu}{\ln\left\lbrack {\sum\limits_{i}{\sum\limits_{u}\;{{\phi_{tb}^{i}(u)}{I^{i}(u)}}}} \right\rbrack}} - {\ln\left( {y_{tb}!} \right)}} \right\}}}}} & \left( {6(} \right.\end{matrix}$

-   -   The maximum likelihood is the solution of set of non-linear        equations:

$\begin{matrix}{{{{\sum\limits_{tb}{\sum\limits_{u}\;{\phi_{tb}^{i}(u)}}} = {\sum\limits_{tb}\frac{\phi_{tb}^{i}y_{tb}}{{\hat{y}}_{tb}}}}\;,{{for}\mspace{14mu}{all}\mspace{14mu} i},{where}}\mspace{11mu}} & \left( {7(} \right. \\{\;{{\hat{y}}_{tb} \equiv {\sum\limits_{i}{\sum\limits_{u}\;{{\phi_{\;{tb}}^{\; i}(u)}{{I^{\; i}(u)}.}}}}}} & \left( {8(} \right.\end{matrix}$

The solution may be solved via the Expectation Maximization (EM)approach:·X _(tb) ^(i)(u)˜Poiss(φ_(tb) ^(i)(u)I ^(i)(u))  (9(

-   -   The likelihood of the complete data:        ln P(x|I ¹ ,I ² ,K)=Σ_(tb)Σ_(i)Σ_(u){−φ_(tb) ^(i)(u)I ^(i)(u)+x        _(tb) ^(i)(u)ln [φ_(tb) ^(i)(u)I ^(i)(u)]−ln(x _(tb)        ^(i)(u)!)}  (10(

-   The EM based algorithm is an iterative procedure. Since the    likelihood depends on the complete data which is only partially    observable, at any iteration step the expectation of the likelihood    is taken with respect to the space of the unobserved data, given the    current set of hypothesized parameters. The result is a function,    Q(I^(i)|I^(i)′) which assigns likelihood to sets I^(i) of model    parameters, given the current set I^(i)′, and given the observed    data y_(tb):

$\begin{matrix}{{Q\left( {I^{i}❘I^{i^{\prime\prime}}} \right)} = {{E\left\lbrack {{{\ln\;{P\left( {x❘I^{i}} \right)}}❘y};I^{i^{\prime}}} \right\rbrack} = {\sum\limits_{tb}{\sum\limits_{i}{\sum\limits_{u}\;\left\{ {{{- {\phi_{tb}^{i}(u)}}{I^{i}(u)}} + {{E\left\lbrack {{{x_{tb}^{i}(u)}❘y_{tb}};I^{i^{\prime}}} \right\rbrack}{\ln\left\lbrack {{\phi_{tb}^{i}(u)}{I^{i}(u)}} \right\rbrack}} + C} \right\}}}}}} & \left( {11(} \right.\end{matrix}$

-   where C is a term which is independent of the intensities I. The    function Q, can be maximized by the following estimate for all uεU:

$\begin{matrix}{{I^{i}(u)} = {\frac{1}{\sum\limits_{tb}{\phi_{tb}^{i}(u)}}{\sum\limits_{tb}{{E\left\lbrack {{{x_{tb}^{i}(u)}❘y_{tb}};{I^{i^{\prime}}(u)}} \right\rbrack}.}}}} & \left( {12(} \right.\end{matrix}$

Assuming conventional Poisson distributions, the expectation of I^(i)can be calculated, resulting in the following expression for E:

$\begin{matrix}{{E\left\lbrack {{{x_{tb}^{i}(u)}❘y_{tb}};I^{i^{\prime}}} \right\rbrack} = {y_{tb}{\frac{{\phi_{tb}^{i}(u)}{I^{i^{\prime}}(u)}}{\sum\limits_{v}{{\phi_{tb}^{i}(v)}{I^{i^{\prime}}(v)}}}.}}} & (13)\end{matrix}$

The EM based algorithm is therefore give by:

$\begin{matrix}{{{{I^{i}(u)} = {\frac{1}{\sum\limits_{tb}{\phi_{tb}^{i}(u)}}{\sum\limits_{tb}{\frac{y_{tb}}{{\hat{y}}_{tb}}{\phi_{tb}^{i}(u)}{I^{i^{\prime}}(u)}}}}},{{for}\mspace{14mu}{all}\mspace{14mu} i\mspace{14mu}{where}}}\mspace{11mu}} & \left( {14(} \right. \\{{\hat{y}}_{tb} \equiv {\sum\limits_{i}{\sum\limits_{u}\;{{\phi_{\;{tb}}^{\; i}(u)}{{I^{i^{\prime}}(u)}.}}}}} & \left( {15(} \right.\end{matrix}$

It is provable that the likelihood is improved at each iteration step.Thus, given a random starting estimator, the EM based algorithm iteratesuntil it converges to a local maximum of the likelihood. Several randomstarts can increase the chance of finding a globally good estimator.

Separate Submissions

Following are examples for the case of two isotopes being submitted intwo separate submissions. The utilization can be performed in a two-stepestimation procedure or in a combined estimation procedure.

In the two-step estimation procedure, the first step comprises thesubmission of the first isotope (i=1) and the estimation of its densitydistribution, I¹(u), using the EM based algorithm. The second stepcomprises the submission of the second isotope (i=2), while the firstisotope is still distributed in the volume. Given the already estimatedÎ¹(u), I²(u) can be estimated by:

$\begin{matrix}{{{I^{2}(u)} = {\frac{1}{\sum\limits_{tb}{\phi_{tb}^{2}(u)}}{\sum\limits_{tb}{\frac{y_{tb}}{{\hat{y}}_{tb}}{\phi_{tb}^{2}(u)}{I^{2}(u)}}}}},{where}} & \left( {16(} \right. \\{{\hat{y}}_{tb} \equiv {{\sum\limits_{u}\;{{\phi_{\;{tb}}^{2}(u)}{I^{2}(u)}}} + {\sum\limits_{u}\;{{\phi_{\;{tb}}^{\; 1}(u)}{{{\hat{I}}^{1}(u)}.}}}}} & \left( {17(} \right.\end{matrix}$

Extension to multiple (e.g., 3, 4 or more) submissions isstraightforward.

In the combined estimation procedure, a first scan is performed aftersubmitting the first isotope and a second scan is performed when bothisotopes are distributed. In other words, the procedure is as follows:submit the first isotope, scan, submit the second isotope and scanagain. The measurements of the first and second scans are denoted byy_(tb) ⁽¹⁾ and y_(tb) ⁽²⁾, respectively. The functional of the firstscan is denoted φ_(tb) ¹⁽¹⁾, and the functionals of the second scan aredenoted φ_(tb) ¹⁽²⁾, φ_(tb) ²⁽²⁾.

-   -   The measurements have the Poisson distributions:        y _(tb) ⁽¹⁾˜Poiss(Σ_(u)φ_(tb) ¹⁽¹⁾(u)I ¹(u))        y _(tb) ⁽²⁾˜Poiss(Σ_(u)φ_(tb) ¹⁽²⁾(u)I ¹(u)+φ_(tb) ²⁽²⁾(u)I        ²(u))  (18(    -   The solution based on the EM approach:

$\begin{matrix}\begin{matrix}{{I^{1}(u)} = {\frac{1}{{\sum\limits_{tb}\;{\phi_{\;{tb}}^{\;{1{(1)}}}(u)}} + {\phi_{\;{tb}}^{\;{1{(2)}}}(u)} + {\phi_{\;{tb}}^{2{(2)}}(u)}}{\sum\limits_{tb}{\left( {\frac{\;{y_{\;{tb}}^{(1)}\;\phi_{\;{tb}}^{\;{1\;{(1)}}}(u)}}{\;{\;\hat{y}}_{tb}^{(1)}} + \frac{\;{y_{\;{tb}}^{(2)}\;\phi_{\;{tb}}^{\;{1\;{(2)}}}(u)}}{\;{\;\hat{y}}_{tb}^{(2)}}} \right){I^{1}(u)}}}}} \\{{{I^{2}(u)} = {\frac{1}{{\sum\limits_{tb}\;{\phi_{\;{tb}}^{\;{1{(1)}}}(u)}} + {\phi_{\;{tb}}^{\;{1{(2)}}}(u)} + {\phi_{\;{tb}}^{2{(2)}}(u)}}{\sum\limits_{tb}{\left( \frac{\;{y_{\;{tb}}^{(2)}\;\phi_{\;{tb}}^{\;{2\;{(2)}}}(u)}}{\;{\;\hat{y}}_{tb}^{(2)}} \right){I^{2}(u)}}}}},{where}}\end{matrix} & \left( {19(} \right. \\{\;{{{\hat{y}}_{tb}^{(1)} \equiv {\sum\limits_{u}\;{{\phi_{\;{tb}}^{\;{1{(1)}}}(u)}{I^{1}(u)}}}}{{{\hat{y}}_{tb}^{(2)}{\sum\limits_{u}\;{{\phi_{\;{tb}}^{\;{1{(2)}}}(u)}{I^{1}(u)}}}} + {{\phi_{\;{tb}}^{\;{2\;{(2)}}}(u)}{{I^{2}(u)}.}}}}} & \left( {20(} \right.\end{matrix}$

The EM iterative process can also be formulated by maximizing theexpected posterior probability (given a proper prior) rather than theexpected likelihood.

For conciseness and simplification of the notations, the isotope andenergy bin indices (i and b, respectively) have been omitted from thefollowing description. It is to be understood, however, that it is notintended to limit the scope of the present invention to the case of asingle isotope or a single energy bin. One of ordinary skill in the artwould appreciate that the following description can be extended to thecase of more than one isotope and/or more than one energy bin as furtherdetailed hereinabove.

In the embodiment in which the expected posterior probability ismaximized, a prior probability P(I)=π_(u)P(I(u)) is assumed on theintensities I. A proper conjugate prior for the Poisson distribution isthe Gamma distribution,

$\begin{matrix}{\left. {{{P\left( {I(u)} \right)} = \left. {{Gamma}\text{(}{I(u)}} \middle| \alpha_{u} \right.};\beta_{u}} \right) = {\frac{\beta_{u}^{\alpha_{u}} + 1}{\Gamma\left( {\alpha_{u} + 1} \right)}{I(u)}^{\alpha_{u}}{\mathbb{e}}^{{- \beta_{u}}{I{(u)}}}}} & (21)\end{matrix}$

Now the function Q is defined as:Q(I|I′)=E[ln P(x|I)p(I)|y;I′].  (22)

Plugging the Gamma prior into Q, and solving for I(u), the following EMiteration for the maximum posterior estimation is obtained:

$\begin{matrix}\begin{matrix}{{I(u)} = \frac{\alpha_{u} + {\sum\limits_{t}{E\left\lbrack {\left. {x_{t}(u)} \middle| y_{t} \right.;I^{\prime}} \right\rbrack}}}{\beta_{u} + {\sum{\Phi_{t}(u)}}}} \\{= {\frac{1}{\beta_{u} + {\sum\limits_{t}{\Phi_{t}(u)}}}\left\lbrack {\alpha_{u} + {\sum\limits_{t}{y_{t}{\frac{{\Phi_{t}(u)}{I^{\prime}(u)}}{\sum\limits_{v}{{\Phi_{t}(u)}{I^{\prime}(v)}}}.}}}} \right\rbrack}}\end{matrix} & (23)\end{matrix}$

In matrix notation, the EM procedure can be written as follows. Let Φ bethe matrix of the views [φ_(t)(u)]_(t,u), and let I, I′, y, α and β berepresented as column vectors. Equation 23 can be written in vector andmatrix notations as:

$\begin{matrix}{I = \frac{\alpha + {I^{\prime} \cdot \left( {\Phi^{T}\frac{y}{\Phi\; I^{\prime}}} \right)}}{\beta + {\Phi^{T}1}}} & (24)\end{matrix}$

where the explicit multiplication and division denote element-wiseoperations, and 1 is a vector (of the appropriate length) consistingsolely of 1's.

When the computational resources are limited, the iterative process canbe divided according to a partition of the view matrix Φ into a set ofsub-matrices (Φ_(k). In this case the intensities can be updatedgradually (using only one sub-matrix at each step) as follows:

$\begin{matrix}{I = \frac{\alpha + {I^{\prime}{\sum\limits_{k}{\Phi_{k}^{T}\frac{y_{k}}{\Phi_{k}I^{\prime}}}}}}{\beta + {\sum\limits_{k}{\Phi_{k}^{T}1}}}} & (25)\end{matrix}$

where y_(k) is the vector of observations that are obtained using theviews of Φ_(k).

The above described algorithm enables identification of the differentenergy level photons (energy signature) emitted from a radioisotope(produced from directly collected photons as well as photons generatedfrom Compton scattering), or a plurality of radioisotopes (e.g.,cocktail) detected by the radiological imaging system. Thus, such analgorithm enables association between various energy level photons andan isotope source. In essence, this algorithm produces for everyradioisotope an energy signature which is composed of the various energyphotons produced thereby in a body as a function of a voxel imaged bythe system.

The following additional example relates to the issue of calculatingattenuation correction simultaneously with body emission. Attenuationcorrection can be important in reducing artifacts (e.g., due to thepresence of low density lungs in the proximity of the heart).Attenuation maps can be obtained using modalities such as CT scans, orthey can be estimated from transmission data, using external sourcescoupled with an appropriate collimation. These methods, however, sufferfrom an increase in complexity and overall scanning time. Additionally,there is a potential crosstalk contamination between the emission andtransmission data.

The present embodiments successfully estimate the density andattenuation solely from the emission data or, in special cases, fromtransmission data. In this example, the isotope and energy bin indices(i and b, respectively) have been omitted from the following descriptionfor conciseness and simplification of the notations. One of ordinaryskill in the art would appreciate that the following description can beextended to the case of more than one isotope and/or more than oneenergy bin as further detailed hereinabove.

Let A(u) be the attenuation of voxel u and let δ_(t)(u,v) be the averagelength of the intersection of voxel v with the lines from (the centerof) voxel u reaching detector t. If there is no such intersection thenδ_(t)(u,v)=0. Additionally, the quantity ψ_(t)(u) is defined in terms ofA and δ as follows:

$\begin{matrix}{{\psi_{t}(u)} = {{\mathbb{e}}^{- {\sum_{v}{{\delta_{t}{({u,v})}}{A{(u)}}}}}.}} & (26)\end{matrix}$

The measurement Y_(t) is now a Poisson random variable with meanΣ_(u)ξ_(t)(u) I(u), where ξ_(t)(u)=Φ_(t)(u) ψ_(t)(u). When the map A(•)is known, the maximum likelihood estimation algorithm presented abovecan be used, by replacing φ_(t)(u) with ξ_(t)(u), for every measurementt and every voxel u, thus obtaining the following maximum-likelihoodupdates:

$\begin{matrix}{{I(u)} = {\frac{1}{\sum\limits_{t}{\xi_{t}(u)}}{\sum\limits_{t}{y_{t}\frac{{\xi_{t}(u)}{I^{\prime}(u)}}{\sum\limits_{v}{{\xi_{t}(v)}{I^{\prime}(v)}}}}}}} & (27)\end{matrix}$

To compute the likelihood of the data, a new (hidden) variableX_(t)(u,v), is defined. X_(t)(u,v) is the number of photons emitted fromvoxel u, directed towards detector t and entered voxel v. Note thatX_(t)(u,v) represents the photon which would have been detected bydetector t in the absence of attenuation. Let X_(t)(u) be the number ofphotons emitted from u and detected in measurement t (recall thatdetector t is associated with measurement t). The number of photonsleaving v and entering the next voxel, v+1, along the line from thecenter of u to the center of detector t is denoted X_(t)(u,v+1).

The likelihood of the completed data can thus be written as:

$\begin{matrix}{\left. {\left. {\left. {P\text{(}X} \middle| I \right.,A} \right) = {\prod\limits_{t}\;{\left\lbrack {\prod\limits_{u}\;{{Poisson}\text{(}{X_{t}\left( {u,u} \right)}}} \middle| {{\phi_{t}(u)}{I(u)}} \right){\prod\limits_{v}\;{{Binomial}\left( {X_{t}\left( {u,{v + 1}} \right)} \middle| {{\mathbb{e}}^{{- {\delta_{t}{({u,v})}}}{A{(v)}}}{X_{t}\left( {u,v} \right)}} \right)}}}}} \right\rbrack,} & (28)\end{matrix}$

and the log-likelihood is:

$\begin{matrix}{\left. {\left. {\ln\; P\text{(}X} \middle| I \right.,A} \right) = {\sum\limits_{t}{\sum\limits_{u}\left\{ {{{{- {\Phi_{t}(u)}}{I(u)}} + {{X_{t}\left( {u,u} \right)}{\ln\left( {{\Phi_{t}(u)}{I(u)}} \right)}} + {\sum\limits_{v \in {l_{t}{(u)}}}\left\lbrack {\left. \quad{{{- {\delta_{t}(u)}}{A(u)}{X_{t}\left( {u,{v + 1}} \right)}} + {{\ln\left( {1 - {\mathbb{e}}^{{- {\delta_{t}{(u)}}}{A{(u)}}}} \right)}\left( {{X_{t}\left( {u,v} \right)} - {X_{t}\left( {u,{v + 1}} \right)}} \right)}} \right\rbrack + C} \right\}}},} \right.}}} & (29)\end{matrix}$

where C represents all the terms that are independent of the parametersI and A. The calculation of the expectation of the log-likelihood, isbase on the expectation of X_(t)(u,v) given Y_(t), I and A:

$\begin{matrix}{\begin{matrix}{\left. {\left. {E\text{[}{X_{t}\left( {u,v} \right)}} \middle| Y_{t} \right.,I,A} \right\rbrack = {\sum\limits_{x_{t}{({u,v})}}{{X_{t}\left( {u,v} \right)}{P\left( {\left. {X_{t}\left( {u,v} \right)} \middle| Y_{t} \right.,I,A} \right)}}}} \\{{= \left. {\sum\limits_{x_{t}{({u,v})}}{{X_{t}\left( {u,v} \right)}{\sum\limits_{x_{t}{(u)}}{P\left( {X_{t}\left( {u,v} \right)} \right)}}}} \middle| {X_{t}(u)} \right.},} \\{\left. {Y_{t},I,A} \right){P\left( {\left. {X_{t}(u)} \middle| Y_{t} \right.,I,A} \right)}} \\{= {\sum\limits_{{x_{t}{(u)}} = 0}^{Y_{t}}{\sum\limits_{{x_{t}{({u,v})}} = {X_{t}{(u)}}}^{\infty}{{X_{t}\left( {u,v} \right)}{P\left( \left. {X_{t}\left( {u,v} \right)} \right| \right.}}}}} \\{\left. {{X_{t}(u)},I,A} \right){P\left( \left( {\left. {X_{t}(u)} \middle| Y_{t} \right.,I,A} \right) \right.}} \\{= {\sum\limits_{{x_{t}{(u)}} = 0}^{Y_{t}}{{P\left( {\left. {X_{t}(u)} \middle| Y_{t} \right.,I,A} \right)}{E\left\lbrack \left. {X_{t}\left( {u,v} \right)} \right| \right.}}}} \\\left. {{X_{t}(u)},I,A} \right\rbrack\end{matrix}{Let}} & (30) \\{{{\psi_{t}\left( {u,v} \right)} = {\mathbb{e}}^{- {\sum_{w < v}{{\delta_{t}{({u,w})}}{A{(w)}}}}}},} & (31)\end{matrix}$

where the notation “w<v” is to be understood as the set of all thevoxels preceding v on the line from u to t (recall that ψ_(t)(u) wasdefined as exp [−Σ_(w)δ_(t)(u,w)A(w)]). To calculate the expectation ofP(X, (u, v)|X_(t)(u), I, A), it is noted that:

$\begin{matrix}\begin{matrix}{\left. {\left. {P\text{(}{X_{t}\left( {u,v} \right)}} \middle| {X_{t}(u)} \right.,I,A} \right)==\frac{\begin{matrix}{P\left( {\left. {X_{\; t}\left( {u,v} \right)} \middle| I \right.,A} \right){P\left( {{X_{t}(u)}} \right.}} \\\left. {{X_{t}\left( {u,v} \right)},I,A} \right)\end{matrix}}{P\left( {\left. {X_{t}(u)} \middle| I \right.,A} \right)}} \\{= \frac{\begin{matrix}{{Poisson}\left( {{X_{t}\left( {u,v} \right)}\left. {{\phi_{t}(u)}{\psi_{t}\left( {u,v} \right)}{I(u)}} \right)} \right.} \\{{Binomial}\left( {{X_{t}(u)}\left. {\frac{\psi_{t}(u)}{\psi_{t}\left( {u,v} \right)}{X_{t}\left( {u,v} \right)}} \right)} \right.}\end{matrix}}{{Poisson}\left( {X_{t}(u)} \middle| {{\phi_{t}(u)}{\psi_{t}(u)}{I(u)}} \right)}} \\{= {{Poisson}\left( {{X_{t}\left( {u,v} \right)} - {X_{t}(u)}} \middle| {\phi_{t}(u)} \right.}} \\\left. {\left( {{\psi_{t}\left( {u,v} \right)} - {\psi_{t}(u)}} \right){I(u)}} \right)\end{matrix} & (32)\end{matrix}$

meaning that

$\begin{matrix}{E\left\lbrack {{{X_{t}\left( {u,v} \right)} - {{X_{t}(u)}\left. {{X_{t}(u)},I,A} \right\rbrack}} = {E\left\lbrack {{{X_{t}\left( {u,v} \right)}\left. {I,A} \right\rbrack} - {E\left\lbrack {{{X_{t}(u)}\left. {I,A} \right\rbrack},{hence}} \right.}} \right.}} \right.} & (33) \\\begin{matrix}{{E\left\lbrack {X_{\; t}\left( {u,v} \right){{{X_{\; t}(u)},I,A}}} \right\rbrack} = {{X_{t}(u)} + {E\left\lbrack {{X_{\; t}\left( {u,v} \right)} - {{X_{\; t}(u)}\left. {I,A} \right\rbrack}} \right.}}} \\{= {{X_{t}(u)} + {{\Phi_{t}(u)}\left( {{\Psi_{t}\left( {u,v} \right)} - {\Psi_{t}(u)}} \right){{I(u)}.}}}}\end{matrix} & (34)\end{matrix}$

The following expectations (E-Step) are thus obtained:

$\begin{matrix}\begin{matrix}{{E\text{[}{X_{t}\left( {u,v} \right)}\left. {Y,I,A} \right\rbrack}=={\sum\limits_{{x_{t}{(u)}} = 0}^{Y_{t}}{P\left( {{X_{t}(u)}\left. {Y_{t},I,A} \right)\left\{ {{X_{t}(u)} +} \right.} \right.}}} \\\left. {{\phi_{t}(u)}\left( {{\psi_{t}\left( {u,v} \right)} - {\psi_{t}(u)}} \right){I(u)}} \right\} \\{= {E\left\lbrack {{{X_{t}(u)}\left. {Y_{t},I,A} \right\rbrack} + {{\phi_{t}(u)}\left( {\psi_{t}(u)} \right){I(u)}}} \right.}} \\{= {{y_{t}\frac{{\phi_{t}(u)}{\psi_{t}(u)}{I(u)}}{\sum\limits_{w}{{\phi_{t}(w)}{\psi_{t}(w)}{I(w)}}}} + {{\phi_{t}(u)}\left\lbrack {{\psi_{t}\left( {u,v} \right)} -} \right.}}} \\{\left. {\psi_{t}(u)} \right\rbrack{I(u)}}\end{matrix} & (35)\end{matrix}$

To get the update I of I′, the complete-data log-likelihood is maximizewith respect to I′ (M-step):

$\begin{matrix}\begin{matrix}{{I(u)} = {\frac{1}{\sum\limits_{t}{\Phi_{t}(u)}}{\sum\limits_{t}{E\left\lbrack {{X_{t}\left( {u,u} \right)}\left. {I^{\prime},A,y} \right\rbrack} \right.}}}} \\{= {\frac{1}{\sum\limits_{t}{\Phi_{t}(u)}}{\sum\limits_{t}\left\lbrack {{y_{t}\frac{{\Phi_{t}(u)}{\Psi_{t}(u)}{I^{\prime}(u)}}{\sum\limits_{w}{{\Phi_{t}(w)}{\Psi_{t}(w)}{I^{\prime}(w)}}}} + {{\Phi_{t}(u)}\left( {1 - {\Psi_{t}(u)}} \right){I^{\prime}(u)}}} \right\rbrack}}}\end{matrix} & (36)\end{matrix}$

The maximization with respect to the attenuations A(u) results intranscendental equations:

$\begin{matrix}{0 = {\sum\limits_{t}{\sum\limits_{u < v}\left\lbrack {{\frac{E\left\lbrack {{{X_{t}\left( {u,v} \right)}\left. {I^{\prime},A,y} \right\rbrack} = {E\left\lbrack {{X_{t}\left( {u,{v + 1}} \right)}\left. {I^{\prime},A,y} \right\rbrack} \right.}} \right.}{{\mathbb{e}}^{{\delta_{t}{({u,v})}}{A{(v)}}} - 1}{\delta_{t}\left( {u,v} \right)}} - {{\delta_{t}\left( {u,v} \right)}{E\left\lbrack {{X_{t}\left( {u,{v + 1}} \right)}\left. {I^{\prime},A,y} \right\rbrack} \right.}}} \right.}}} & (37)\end{matrix}$

These equations can be solved using the approximation:1/(e ^(δ) ^(t) ^((u,v)A(v))−1)≈1/(δ_(t)(u,v)A(v))−1/2.  (38)

With the observation that, typically, the product δ_(t)(u,v) A(v) isclose to unity, one obtains:

$\begin{matrix}{{{A(v)} = \frac{\sum\limits_{t}{\sum\limits_{u}{{\Phi_{t}(u)}{{I(u)}\left\lbrack {{{\overset{\_}{x}}_{t}\left( {u,v} \right)} - {{\overset{\_}{x}}_{t}\left( {u,{v + 1}} \right)}} \right\rbrack}}}}{\frac{1}{2}{\sum\limits_{t}{\sum\limits_{u}{{\Phi_{t}(u)}{{I(u)}\left\lbrack {{{\overset{\_}{x}}_{t}\left( {u,v} \right)} + {{\overset{\_}{x}}_{t}\left( {u,{v + 1}} \right)}} \right\rbrack}{\delta_{t}\left( {u,v} \right)}{I(u)}}}}}},} & (39)\end{matrix}$

where (interpreting the relation “w<v” as before):

$\begin{matrix}{{{{\overset{\_}{x}}_{t}\left( {u,v} \right)} = {{y_{t}\frac{{\phi_{t}(u)}{\psi_{t}(u)}{I(u)}}{\sum\limits_{w}{{\phi_{t}(w)}{\psi_{t}(w)}{I(w)}}}} + {{\phi_{t}(u)}{{I(u)}\left\lbrack {{\psi_{t}\left( {u,v} \right)} - {\psi_{t}(u)}} \right\rbrack}}}}{{\psi_{t}\left( {u,v} \right)} = {{\mathbb{e}}^{- {\sum\limits_{w\; < \; v}{{\delta_{\; t}{({u,w})}}{A{(w)}}}}}.}}} & (40)\end{matrix}$

As will be understood by one ordinarily skilled in the art, although thesame notation, A, is used for the current value of the attenuation andthe updated value thereof, no confusion can occur, as it is a commonpractice to interpret each of the above formulae as an assignment. Thus,for example, A(v) appearing in the LHS of Formula 39 represents anupdated value, while A(w) appearing in the RHS of Formulae 40 representsa current value.

The following is a description of a method for calculating attenuationmap using transmission data, in accordance with various exemplaryembodiments of the invention.

For a single transmitting source, a transmitting voxel s, for which theintensity I(s) is known (with zero attenuation) is added. For all othervoxels u≠s, the intensity I(u) is zero. The only non-zero expectationsare therefore:x _(t)(s,u)=E[X _(t)(s,u)|A,y]=y_(t)+φ_(t)(s)[ψ_(t)(s,u)−ψ_(t)(s)]I(s),  (41)

and the maximum likelihood updates of the attenuations are:

$\begin{matrix}{{A(u)} = {\frac{\sum\limits_{t}{{{\Phi_{t}(s)}\left\lbrack {{{\overset{\_}{x}}_{t}\left( {s,u} \right)} - {{\overset{\_}{x}}_{t}\left( {s,{u + 1}} \right)}} \right\rbrack}{I(s)}}}{\frac{1}{2}{\sum\limits_{t}{{{\Phi_{t}(s)}\left\lbrack {{{\overset{\_}{x}}_{t}\left( {s,u} \right)} + {{\overset{\_}{x}}_{t}\left( {s,{u + 1}} \right)}} \right\rbrack}{\delta_{t}\left( {s,u} \right)}{I(s)}}}}.}} & (42)\end{matrix}$

In the “blank scan” case, where detection is made with no patient in thescanner, there is no attenuation and the function B_(t)(s)=I(s)φ_(t)(s)represents the expected counts measured by detector t. B_(t)(s) can bemeasured using a (periodic) blank scan, scaled for the transmissionscan, and used in the estimation of the attenuation coefficients, asfollows:

$\begin{matrix}{{{A(u)} = \frac{\sum\limits_{t}{{B_{t}(s)}\left\lbrack {{{\overset{\_}{x}}_{t}\left( {s,u} \right)} - {{\overset{\_}{x}}_{t}\left( {s,{u + 1}} \right)}} \right\rbrack}}{\frac{1}{2}{\sum\limits_{t}{{{B_{t}(s)}\left\lbrack {{{\overset{\_}{x}}_{t}\left( {s,u} \right)} + {{\overset{\_}{x}}_{t}\left( {s,{u + 1}} \right)}} \right\rbrack}{\delta_{t}\left( {s,u} \right)}}}}}{{where},}} & (43) \\{{{\overset{\_}{x}}_{t}\left( {s,u} \right)} = {y_{t} + {{{B_{t}(s)}\left\lbrack {{\psi_{t}\left( {s,u} \right)} - {\psi_{t}(s)}} \right\rbrack}.}}} & (44)\end{matrix}$

When there is a set S of transmitting sources, a separate calibrationscan can be performed for each source sεS, so as to estimate B_(t)(s)for every measurement t. The reason for separating the blank scans isthat the counts in measurement t can potentially originate fromdifferent sources. This is because the transmission beams may overlap.Note also that the existence of different sources implies differentintersections with the voxels, for any given measurement. In this case,an iterative procedure can be derived from Formula 39 as follows:

$\begin{matrix}{{{A(u)} = \frac{\sum\limits_{t}{\sum\limits_{s}{{B_{t}(s)}\left\lbrack {{{\overset{\_}{x}}_{t}\left( {s,u} \right)} - {{\overset{\_}{x}}_{t}\left( {s,{u + 1}} \right)}} \right\rbrack}}}{\frac{1}{2}{\sum\limits_{t}{\sum\limits_{s}{{{B_{t}(s)}\left\lbrack {{{\overset{\_}{x}}_{t}\left( {s,u} \right)} + {{\overset{\_}{x}}_{t}\left( {s,{u + 1}} \right)}} \right\rbrack}{\delta_{t}\left( {s,u} \right)}}}}}},{where},} & (45) \\{{{\overset{\_}{x}}_{t}\left( {s,u} \right)} = {{y_{t}\frac{{B_{t}(s)}{\psi_{t}(s)}}{\sum\limits_{r}{{B_{t}(r)}{\psi_{t}(r)}}}} + {{{B_{t}(s)}\left\lbrack {{\psi_{t}\left( {s,u} \right)} - {\psi_{t}(s)}} \right\rbrack}.}}} & (46)\end{matrix}$

Diagnosis in a Multidimensional Space

There is also provided in accordance with an exemplary embodiment of theinvention, a method of diagnosis, comprising:

measuring a plurality of patient parameters to determine a patientstate; and

identifying a disease state by matching the patient state using aplurality of said plurality of parameters. Optionally, said patientstate comprises a dynamic patient state.

In an exemplary embodiment of the invention, said patient state includeskinetic information of at least one biochemical at a temporal resolutionof better than 1 second.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of acquiring a patient profile, comprising:

providing at least one material to a patient;

scanning an interaction of said material with the patient at a rate ofover once a second; and

building a complex profile of the patient including one or more of akinetic profile of a parameter related to said material and a pluralityof concurrently measured patient parameters.

In an exemplary embodiment of the invention, said building comprisesbuilding based on a previous estimated kinetic profile of the material.

There is also provided in accordance with an exemplary embodiment of theinvention, apparatus for carrying out the methods described herein,comprising circuitry for said building.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of selecting a material for diagnosis, comprising:

estimating a patient physiological state in the form of a complexprofile;

selecting a desired differentiation of patient state; and

selecting a material to have an interaction with the patient whichprovides said differentiation. Optionally, said material is associatedwith a complex profile which is matched to said patient profile for saidselecting.

There is also provided in accordance with an exemplary embodiment of theinvention, a database comprising at least 20 substances, each one with acomplex substance profile. Optionally, the database comprises at least50 substances. Optionally, the database comprises at least 150substances.

An aspect of some embodiments of the invention relates to a complexsubstance profile. In an exemplary embodiment of the invention, theprofile includes intra-body location and/or tissue specific behavior,for example, metabolism and/or uptake. Optionally, the profile is of atime dependent parameter, such as change in metabolic rate over time.Optionally, static parameters, such as “expected effect” are providedand/or determined. In an exemplary embodiment of the invention, theprofile includes an interaction of a substance with multiplephysiological parameters, for example, parameters measured using methodsand apparatus as described herein. In some embodiments, the profileincludes an interaction or an effect on the behavior of the substancedue to a previous physiological condition or perturbation, for example,the provision of another substance.

In an exemplary embodiment of the invention, the profile includesinformation on the behavior of a substance in short time frames, forexample, tens of seconds, seconds, or fractions of seconds.

An aspect of some embodiments of the invention relates to considering aphysiological state of a patient as a complex of multiple physiologicalparameters. In an exemplary embodiment of the invention, diagnosing apatient comprises identifying a patient's state in an N-space ofparameters, optionally in on a relatively continuous scale. Optionallydiagnosis is carried out by selecting a material which when applied tothe patient will be affected in a noticeable manner dependent on thestate of the patient. In an exemplary embodiment of the invention, thescale used for at least 3, at least 5, at least 10 or more orintermediate numbers of dimensions has at least 5, at least 10, at least20, at least 40 or intermediate or higher numbers of meaningful levels.This is in contrast to typical medicine where usually a small number ofthreshold values is provided. Optionally, if the patient state issimplified, the simplification misrepresents less than 30%, less than20%, less than 10%, less than 1% or intermediate percentages of thespace, the space being sampled at uniform intervals.

In an exemplary embodiment of the invention, the physiological state ofthe patient is perturbated, for example by providing a substance, anddiagnosis is based, at least in part, on the reaction of thephysiological state to the perturbation.

An aspect of some embodiments of the invention relates to acquiringkinetic pharmacological information relating to a substance. In anexemplary embodiment of the invention, a portion of the body is scannedat a rate high enough to acquire kinetic information about thesubstance, for example, uptake, metabolism and/or physiological effect.In an exemplary embodiment of the invention, the information collectedcomprises an indication of patient kinetics. In an exemplary embodimentof the invention, the information collected comprises an interactionbetween the kinetics of a plurality of substances.

In an exemplary embodiment of the invention, the scanning comprisesscanning using florescent imaging of fluorescently tagged materials.

FIG. 125 is a schematic diagram of a configuration for acquiring and/orusing multi-parametric information, in accordance with an exemplaryembodiment of the invention;

FIG. 126 is a flowchart of a method of acquiring and/or usingmulti-parametric information, in accordance with an exemplary embodimentof the invention;

FIG. 127 is a simplified space indicating a diagnosis and a normalphysiological state, in accordance with an exemplary embodiment of theinvention;

FIG. 128 shows a simplified two dimensional space showing a complexdiagnosis, in accordance with an exemplary embodiment of the invention.

Complex and/or Multi-Parameter Profiles

In the above section on an expert system, the use of some types ofmulti-parameter profiles has been described. In this section, interalia, more general uses and/or profile types are described.

In an exemplary embodiment of the invention, the scanning system asdescribed above is used to generate a complex profile of humanphysiology. Alternatively or additionally, a complex profile ofsubstance is generated and/or used for diagnosis.

In an exemplary embodiment of the invention, the complex profile(s)includes pharmakinetic information at a relatively high temporal and/ortissue type resolution, for example, 10 seconds, 5 seconds, 1 second,100 milliseconds, 50 milliseconds of faster or intermediate values. Inan exemplary embodiment of the invention, the complex profiles are usedto generate a diagnosis of patient state and/or define a suitable regimefor treatment.

Exemplary Data System

FIG. 125 shows an exemplary configuration which may be useful foracquiring and/or using complex profiles, in accordance with someexemplary embodiments of the invention.

A scanner 20006, for example, as described above or any other type offast scanner, for example a florescent imaging scanner that imagesfluorescently tagged materials or other scanners that image taggedmaterials or devices that track non-tagged materials, such as localizedNMR (or other) spectroscopy or infra-red imaging, is used to acquireinformation about a patient 20002. Alternatively or additionally,genomic information, such as mRNA expression or protein expression isacquired, for example, using a gene chip. Alternatively or additionallyto fast scanning, in some embodiments of the invention the scanning isrelatively slow and/or maybe invasive, for example, blood tests, bloodpressure and oxygenation measurement, mechanical measurements (e.g.,ejection fraction) and/or any known physiological measurement. Thisinformation can include various physiological parameters of the patientand/or substances introduced therein, for example, substanceconcentration, metabolism, analyte levels, rates of change and/or fluidflow. Alternatively or additionally, the information comprises dynamicinformation, for example changes over time or changes in response to anaction on the patient. Alternatively or additionally, the informationcomprises an association with particular body and/or tissue locationinformation.

A controller 20004, optionally connected to scanner 20006, may be usedto store, compare, analyze and/or otherwise use multi-parameter profilesand/or other complex profiles. Optionally, controller 20004 builds up aprofile based on scanning results. A user input 20008, for example, adisplay and/or keyboard are optionally used to control controller 20004and/or display results of controller 20004.

In an exemplary embodiment of the invention, the complex profile data isstored or organized in a tabular form, for example a multi-dimensionaldata table having, inter alia, some or all of the following dimensions:

(a) intrabody location, including, for example, tissue type and/ortissue location and/or including resolution level (e.g., cellular level,tissue level, organ level, body part level);

(b) diagnostic or body state definition;

(c) measured parameters, for example, biochemical concentrations(including blood analyte levels such as glucose and insulin) oraggregate measurements (e.g., blood pressure), which may include patientinformation, such as age and weight; and

(d) state of patient, for example, at rest, standing, after mechanicalstimulation and/or after administration of substance.

Coordinates (discrete or continuous) in the dimensions define cellswhich can include, for example, values of measured parameters, sets ofparameters (e.g., a temporal series) and/or functional and/orstatistical definitions of values and distributions.

This inter-relationship between various dimensions may be used to definea parameter space in which searching and/or other activities are carriedon.

It should be appreciated that this data structure need not be stored asa table, even if its logical structure is that of a table. Inparticular, whole portions of the table may be blank (for lack of dataand/or meaning), or be defined as a function or statistics.Alternatively or additionally, other data organization methods are used,which may use the above informational items as indexes of some type. Insome cases, for at least some of the space, one or more dimensionsand/or ranges of coordinates may be collapsed, for example, a range ofstates may be collapsed into a single meta-state. Such collapsing mayalso be carried out (e.g., temporarily) while viewing and/or analyzingthe data.

It should be noted that a coordinate may include dynamic information,for example a series of absolute or relative changes over time, ratherthan a single value.

As will be described below, controller 20004 may relate to a patientcomplex profile 20010 (or more than one, for various situations). In anexemplary embodiment of the invention, complex profile 20010 includes amulti-parameter table 20012, at least one time dependent measurement20016 and/or at least one location dependent parameter 20014.

As will be described below, controller 20004 may relate to one or moresubstance complex profiles 20018. In an exemplary embodiment of theinvention, complex profile 20018 can include a multi-parameter table20026, intrabody-location dependent information 20024, substancedescription 20020 and/or additional information 20022. Optionally, thecomplex profiles define, for at least some points in the space, atrajectory defining the interaction of the substance (or other stimulus)with a patient located in that point in space. Optionally, the complexprofile includes temporal information indicating different interactionsat different time delays. Optionally, the complex profile definescumulative interactions and/or transient interactions of a substance.

In addition, for example as described below, controller 20004 mayinclude or be associated with an additional database defining positiveand/or negative areas in the space. While a “goodness” value may beassociated with some or all points in space, optionally, a set of areasthat are desired patient states are defined as boundaries of areas.

While this description suggests that the controller is located at thescanner and patient, this is not necessarily the case. For example, fordiagnosis, a controller may be located at a doctor's office, receivemeasurements and generate a diagnosis. Any one of the data sourcesand/or controller may be provided locally and/or remotely, depending onthe implementation. In some cases, a simplified database is storedlocally and a more complete database and/or processing algorithm isremote. In an exemplary embodiment of the invention, the data comprisesone or more of patient data, clinic data, hospital data, healthcaresystem data, country data and/or international data, which areoptionally accesses in a hierarchical manner and/or as slices relatingto the patient.

Exemplary Process

FIG. 126 is a flowchart of a process of acquiring and/or using complexprofiles in accordance with an exemplary embodiment of the invention. Itshould be appreciated that some embodiments of the invention involvepracticing only parts of this process.

At 20102, a patient is scanned, for example using methods describedabove and/or using other means, for example invasive and/or non-invasivesensors as known in the art. In an exemplary embodiment of theinvention, the scanning measures multiple physiological parameters ofthe patient, optionally organ and/or tissue specific. In an exemplaryembodiment of the invention, at least one of the measured parameters isa biochemical parameter sampled at a high rate, for example, faster thanonce in ten seconds or once a second. In an exemplary embodiment of theinvention, the sampling is made fast enough to provide usefulinformation on a substance having a pharmakinetic behavior at those timescales.

At 20104, a patient profile is optionally generated, for example, bydetermining coordinates for the patient state in the above space.Optionally, the profile generated for the patient includes anuncertainty factor, which may be represented, for example, by indicatinga cloud in the space with the density of the cloud depending on thecertainty level of the determination.

In an exemplary embodiment of the invention, the space comprises atleast 5, at least 10, at least 20, at least 30 or a smaller,intermediate or larger number of body area and/or tissue types.

In an exemplary embodiment of the invention, the space includes at least2, at least 4, at least 10, at least 40, at least 100 or a smaller,intermediate or greater number of measured physiological parameters.

In an exemplary embodiment of the invention, the space includes at least3 at least 10, at least 30 or a greater, smaller or intermediate numberof patient classification data, such as height, genomic markers, raceand/or age.

In an exemplary embodiment of the invention, time frames for temporaldata includes at least 5 data points, at least 10 data points, at least20 data points or a smaller, intermediate or greater number of points.

In an exemplary embodiment of the invention, a profile comprises atrajectory in space and may include the above number of points fortemporal data.

In an exemplary embodiment of the invention, a similar process is usedto generate a profile of a substance, by measuring its dynamic behaviorin the above space (e.g., after application to the patient). Forexample, for a body tissue type/location, and other physiologicalparameters, the values of metabolism or uptake (depending on themeasurement method) can be indicated as values in space. In an exemplaryembodiment of the invention, the values are measured as a time seriesfor a particular cell in the space. Alternatively or additionally, thecorrelation between the values and changes in the body state aretracked, for example, a substance may change in measured values as heartrate goes up, wherein each heart rate corresponds to a differentpoint/cell in space. The change in heart rate may be induced.Optionally, for different conditions, different profiles of thesubstances are achieved, which profiles can be combined into a singlecomplex profile that includes the condition as a dimension (e.g.,standing, sleeping, sitting).

FIG. 127 shows a simplified two dimensional space 20202 for illustratingthe results of scanning in accordance with an exemplary embodiment ofthe invention.

An area 20204 indicates a normatively healthy state encompassing a rangeof sets of values for the two (in practice possibly more) parameters.Optionally, improved health states are indicated by sub areas 20208 (ofan area 20206) and 20210. In some cases, a disjoint health area exists,for example an area 20212 with an optional increased health area 20214.Optionally, each point in space is associated with a value indicating“health” that is functionally based on the coordinates and/or onobservations.

In an exemplary embodiment of the invention, a non-health state isdefined as any point outside of the marked “health areas. Optionally,however, one or more particular dangerous or unacceptable states 20216are defined as well. In an exemplary embodiment of the invention, adegree of unhealth is defined as a distance between a point in space anda healthy area. Optionally, different diagnoses are associated withdifferent distances and/or relative positions. Alternatively oradditionally, diagnoses are associated with trajectories in space.Alternatively or additionally, a composite score is provided.Alternatively or additionally, the score depends on estimated quality oflife, pain and/or risk.

A reference 20218 indicates a trajectory of a patient state in space. Aplurality of momentary states 20222, 20224, 20226 and 20228 indicate ameasurement of the patient state. As can be seen, the patient variesbetween points, in the example shown in a repetitive manner. In somecases, the behavior of the trajectory is chaotic, for example, with oneor more attractors. Optionally, the morphology, position and/or timevalues for the trajectory are used for diagnosis. It should be notedthat also healthy states can be defined as trajectories and/or otherwisebe dynamic. Parameter values (e.g., blood glucose levels used ascoordinates in space) can also be defined as a single point whichindicates a distribution of values, statistical properties, attractorsand/or a trajectory between values.

It should be noted that the health values may be obtained in variousmeans, including, for example, based on the patient's own parametersand/or based on normative values collected for a population.

Also shown in FIG. 127 is a point 20230 which is nearly encompassed by ahealthy area but is not part of the healthy area. In an exemplaryembodiment of the invention, the diagnosis of the patient relatesdirectly to the N-dimensional space (e.g., 20202) and not to dimensionsof the space in a piecewise manner. As more specifically shown in agraph 20300 of FIG. 128, it is possible for a point 20304 to be outsideof a healthy area 20302, while still being within the range values ofprojections of the area into lower dimension spaces. In typicaldiagnosis situations, one of two approaches is normally taken, eitherprocessing parameters one at a time or collapsing multiple parametersinto a single measure. A BMI (body mass index) is an example of acomposite measure which does not capture the intricacies of interactionbetween weight and height and completely ignores body form, metabolism,exercise level and other important parameters. Further, the “metabolic Xsyndrome” which is a composite of 5 (or so) measures, also simplifiesthe real space to avoid complexities. Further, in some cases there is acorrelation between measured parameters. Typically, what is done issimply assume a fixed relationship 20306 and squander the informationprovided in area 20302. In a typical situation, relationship 20306 isrealized as an area, for example, a rectangle and not a thin line.

In an exemplary embodiment of the invention, the use of a complexN-dimensional space (and optionally trajectories through space) anddiagnosis based on simultaneous attention to multiple parameters enablessuch inclusions to be correctly identified. In an exemplary embodimentof the invention, the attention is given to at least 2, 3, 4, 5, 7, 10,20, 50 or more or intermediate numbers of parameters.

In some embodiments, at least some of the dimensions are collapsed, atleast for part of the diagnosis, for example, if there is missingmeasurement information or if the space is not populated withinformation.

In an exemplary embodiment of the invention, the acquired data isprocessed to help tease apart dependencies. Optionally, the processingindicates areas where two parameters are possibly less than perfectlycorrelated, which areas may benefit from additional measurement. Whileall the measurements are optionally acquired substantiallysimultaneously (e.g., in a time frame of less than 10 minutes, 1 minute,10 seconds, 1 second or less), sequential acquisition may be practicedin some embodiments of the invention. In an exemplary embodiment of theinvention, new disease states and/or types are defined based onidentified points like point 20304 or based on trajectories.

In an exemplary embodiment of the invention, instead of providing afixed diagnosis, for example “type II diabetes” the diagnosis relates tothe actual degree of unhealth, for example, the distance (in somemetric) from the nearest or a desirable normatively healthy area.

In an exemplary embodiment of the invention, the diagnosis takes intoaccount not only the distance but also uncertainty factors, for example,uncertainties in measurements. A reference 20220 (FIG. 127) indicates acloud of uncertainty relating to a measurement of point 20228.

Alternatively or additionally, the diagnosis takes into account theshape of the trajectory of the patient state (or monitored parametervalue) and/or a spatial distribution and/or density of states and/orvalues (e.g., without tracking the ordinal relationship between points).

Referring back to FIG. 126, additional methods are contemplated. In oneexample, the patient is perturbated (20106), for example, by an impulse(e.g., a short exercise) or by a continuous activity (e.g.,vasodilatation materials provision). In an exemplary embodiment of theinvention, changes in patient state due to the perturbation and/orcaused by the perturbation (e.g., to one or more measured parameters),are tracked (20108). It should be noted that the perturbation willgenerally cause a change in patient state. Optionally, the trajectory ofthe change and/or distribution of state points are used to fine tune adiagnosis (20112) of the patient. Alternatively or additionally, theperturbation is used to generate a more complex profile for thesubstance being tracked, for example by showing values for otherconditions. Alternatively or additionally, the perturbation can providea set of measurements which may reduce the uncertainty of measurementfor a single patient state. Alternatively or additionally, theperturbation shows the stability of the patient in his physiologicalstate and/or initiates a trajectory in space, either or both of whichmay be used as a means for diagnosis, for example by comparing againstnorms. Alternatively or additionally, the perturbation is used togenerate a kinetic profile of the patient and/or a substance (20110).

In a particular example, perturbation comprises administering anothersubstance. The measured values can include, for example, the interactionbetween the substances (e.g., effect of ability to measure), effect ofone or both substances on the physiological state and/or values for oneor both substances as the physiological state changes due to the otheror both substances.

In another method, once a patient profile is known, a tracer material isselected (20114) so as to provide differentiation for what the profileshows in a later scan (20116). In particular, a tracer which will not beabsorbed due to patient state need not be used. Similarly, the tracer isoptionally selected and/or formulated so as to meet both dataacquisition limitations and need to generate a measurable difference.Optionally, this selection is based on a profile associated with thematerial. Optionally, a database of materials and complex profiles isstored. In one example, if there is a problem that can be metabolic orabsorption based, a tracer affected mainly by metabolism will be uselessfor absorption problems. Thus by first determining what the underlyingproblem is, a tracer and/or scanning protocol that will provide usefulinformation on the metabolic (or absorption) problem, can be selected

In another method, the patient is scanned with a material having a knowncomplex profile. By comparing (20118) the actual results to anticipatedresults, a physiological model of the patient may be extracted and/oridentified. In an exemplary embodiment of the invention, the model isfound by searching the space of patient profile for a profile that actsin a manner similar to the observed manner. In another example, amathematical model that links the measured parameters to the knownprofile and/or kinetics is generated and/or tuned.

It should be appreciated that the dimensions of the patient profilespace and the material profile space need not match perfectly.Optionally, a mapping function between dimensions is provided by a user.

In an exemplary embodiment of the invention, diagnosis uses an expertsystem, for example a rule based system or a neural network. Inlower-dimension cases, a visual method is optionally used.

In an exemplary embodiment of the invention, the patient profile spaceis used to store data about all patients and patient types. Optionally,the space is updated continuously as more data is acquired. Optionally,studies, as carried out, are combined into the space to populate emptyspaces and/or reduce uncertainty in existing spaces. As new informationabout studies surfaces, the data may be reintegrated into the space.Optionally, when a patient profile and/or material profile are missing,these may be interpolated from existing data. Optionally, an expert(e.g., human) opinion is provided, for example, to suggest relevant datato be interpolated between and/or weights. In an exemplary embodiment ofthe invention, a user can input constraints that prevent a diagnosisfrom extending in the direction of certain coordinate values.Alternatively or additionally, such constrains can be used to guide adiagnosis process, including a step-by-step diagnosis process.

In an exemplary embodiment of the invention, health definitions areprovided based on an asymptomatic population and/or time in a patient'slife. Alternatively or additionally, health and/or unhealth areas are atleast partially defined based on accepted allowed ranges and/orrisk-indicating values.

Administrations of Multiple Isotopes

The present embodiments comprise an apparatus and a method forradiation-based imaging of a non-homogenous target area having regionsof different material or tissue type or pathology. The imaging usesmulti-dimensional data of the target area in order to distinguish thedifferent regions. Typically the multi-dimensional data involves time asone of the dimensions. A radioactive marker has particulartime-absorption characteristics which are specific for the differenttissues, and the imaging device is programmed to constrain its imagingto a particular characteristic.

The result is not merely an image which concentrates in the tissue ofinterest but also, because it is constrained to the tissue of interest,is able to concentrate imaging resources on that tissue and thus producea higher resolution image than the prior art systems which arecompletely tissue blind.

Reference is now made to FIG. 129, which illustrates a simple Geigercounter taking an image of a target according to the prior art. Geigercounter 9310 is placed in association with target 9312 and absorbs anyradioactive particles that come its way. In general the radioactiveparticles arriving at the Geiger counter arrive from somewhere withincone 9314. Geiger counter 9310 has no information as to the depth fromwhich the particle comes and cannot even distinguish between particlesarriving from different directions within the cone. Thus in principleprior art Geiger counter 9310 gives low resolution one dimensionalinformation.

If Geiger counter 9310 is now moved to different positions over thesurface of the target then the data from the different positions can bebuilt up into a low resolution two-dimensional image.

One way of increasing the resolution of Geiger counter 9310 is to makeit smaller. Then cone 9314, whilst retaining the same geometry, giveshigher resolution data.

A detector 9310 takes (y_(t))_(t=1) ^(T) samples to form a data set,which would typically be a two-dimensional image of the target from agiven direction.

Reference is now made to FIG. 130, which is a simplified diagram showinghow three-dimensional information can be obtained from a target 9312.Parts that are the same as in previous figures are given the samereference numerals and are not referred to again except as necessary forunderstanding the present embodiment. A second Geiger counter 9016 isplaced essentially at right angles to first Geiger counter 9310 andobtains a similar kind of image to Geiger counter 9310. However, sincethe two cones overlap, the images produced can be cross-correlated toinfer the presence of hot or cold radiation sources in three dimensions.

Reference is now made to FIG. 131, which is a sequence of graphsillustrating the different absorption characteristics for differenttissues of a given radioactive marker. Typical markers that may beconsidered are thalium 201 and technitium 99. FIG. 131A indicates atypical absorption characteristic of thalium 201 for blood, thalium 201being a particularly good marker for blood. The marker is generallyabsorbed by the blood fairly rapidly following digestion and thengradually disappears from circulation as it is taken up by the varioustissues and organs including the kidneys. Marker material from thetissues eventually finds its way back into the blood for excretion. Thatwhich is absorbed by the kidneys is excreted directly and does notreturn to the circulation.

FIGS. 131B, 131C and 131D show time absorption characteristics fortechnitium 99 for different tissues, and it will be seen that thecharacteristic tracings are generally curved but peaks at differenttimes for the different tissues.

The principle on which the present embodiments are based is as follows:Considering the graphs in FIG. 131, it will be apparent that a regionbelonging to a single tissue will behave in a uniform manner as regardssignal intensity. That is to say, a given marker will be taken up andthen expelled at the same rate from a given tissue, whereas this ratewill be different for other tissues. If therefore a series of successiveimages are taken of the target and the images are analyzed region byregion for rates of change of intensity, a particular desired regionbecomes identified by virtue of having rates of change in intensity thatfit with a given characteristic. The regions are distinguishable in thisway even if the region of interest is heavily overlapped with otherregions.

Reference is now made to FIG. 132, which shows apparatus forradiation-based imaging of a non-homogenous target area. Apparatus 9320comprises an imaging unit 9322 which itself consists of a series ofsmall Geiger counters 24.1 . . . 24.n arranged on an imaging head. Theimaging unit is controlled by motion controller 9326 to take readingsfrom different locations around the target area. Preferably, the motionof the imaging head is controlled by software via servo-motors. Inaddition the motions, either of the individual Geiger counters or ofgroupings of the Geiger counters, are also controlled by software viaservo-motors.

In a preferred embodiment, the signals received from the individualGeiger counters are summed to form a three-dimensional image of thetarget area. The person skilled in the art will appreciate that thesystem could also be based on a two-dimensional image. In either case,the signals are fed to an image analyzer 9328, where the signals areanalyzed to form images.

In the preferred embodiments, the image analyzer uses the marker uptakecharacteristics to compare successive images and identify regions ofparticular interest, and then to concentrate imaging resources on thoseregions. That is to say the image analyzer is in fact able to controlfurther operation of the imager.

Reference is now made to FIG. 133, which a simplified flow chartillustrates the image analysis process that is carried out by analyzer9328 in the case of a single marker. Preferably a series of images ofthe same views are taken at different times, stage 9330, and athree-dimensional overall image of the target is formed for each time.The analyzer then analyzes each of the three-dimensional overall imagesfor local intensities at different locations around the target, stage9332. The local intensities are noted and the same locations on thedifferent images are superimposed in stage 34. From thesuperpositioning, local rates of change of intensity between the imagesmay be obtained in stage 9336. The rates of change are compared with thepre-obtained characteristics for the marker with the different tissuesin stage 9338, and the data are then constrained to those localities,which conform to the desired predetermined characteristics in stage9340. As a result the imaging process can be used to identify andconcentrate on localities of interest and data from other localities canbe jettisoned. Consequently, the image analysis is able to concentrateits resources on the tissues of interest and a higher resolution finalimage can be produced.

It will be appreciated that in many cases two types of tissue may besuperimposed, of which only one of the tissues is of interest. In thiscase it is of equal importance both to exclude the one tissue that isnot of interest and to include the tissue that is of interest. It may bethat the best marker for one tissue may not be the best marker for theother tissue. The system as described with respect to FIGS. 132 and 133may be adapted to use with two or more markers, as will be explained,below, in relation to FIG. 134.

Each marker produces a radioactive particle of different energy level,and therefore the data from the different markers can be collected andsummed separately to form different images. Mathematically the differentdata sets obtained from the different energy level signals may betreated as different dimensions of a multi-dimensional vector. For eachof the marker-images the appropriate characteristics are used toidentify the tissues of interest, and the results are cross-checkedbetween the different markers. The different tissues are mapped and theimage analysis can concentrate on the area of interest. As a result thesystem uses both time and particle energy as separate dimensions inaddition to the spatial dimensions in order to characterize or map thetissues.

As a result the image analysis unit is able to produce a final resulttreating the various tissue regions as separate entities. Furthermore,as the system is aware of the regions as entities it is able to furtherdirect the imaging process to concentrate on the regions of interest.

An example in which regions at least partially overlap is the heart.Generally, scans of the heart are interested in the muscular walls ofthe heart. Although the chambers of the heart are filled with blood, anysignal coming from the blood is in fact noise to this kind of scan. Itis therefore advantageous to carry out an imaging process that is ableto positively identify signals from the muscular heart walls and at thesame time exclude signals from the blood.

Referring now to FIG. 134, and in a preferred embodiment, the patientingests two markers, thalium 201 and technetium 99. The first of theseis an effective blood marker and two successive thalium images are shownin FIGS. 134A and 134B, and the second is more effective at markingmuscle tissue and two successive images thereof are shown in FIGS. 134Cand 134D. The heart is imaged at intervals chosen both for thecharacteristic for thalium 201 in blood and for the characteristic oftechnetium 99 in muscle. The result is a series of images for each ofthe markers. The series for thalium 201 may be constrained to show theregions of blood quite clearly, and to filter out other regions.

A blood vessel, on the left, is shown clearly in 6A and more faintly in6B where the thalium has mostly been flushed out. The series fortechnetium 99, FIGS. 134C and 134D show muscle wall structures. 6Aappears to show a larger structure on the right, but in fact all that itis showing is that much technetium has not yet been absorbed in themuscle. The second image 6D may therefore be used to constrain the firstimage 6C to show only the muscle walls regions. The two series of imagesmay then be superimposed to filter out from the technetium 99 images 6Cand 6D anything that appears strongly in the thalium images 6A and 6B.The filtering may additionally remove anything that appears strongly inboth images and as coming from outside the region.

In the above example, two regions were of respectively positive andnegative interest, meaning one for concentrating on and the other forfiltering out. It will be appreciated that several regions or severaltissue types may be of positive interest or there may be any combinationof regions with just one being of positive interest. Alternatively allregions may be of positive interest but importance may be attached todiscriminating between the different signals from the different regions.

The system is able to use the mapping to generate an image comprisingthe different tissue regions as distinct entities. As a consequence ofthe mapping process, the system is able to be aware electronically ofthe different regions and thus control both the imaging head and theanalysis unit to concentrate their resources on specific regions. Theresult is greater resolution for the regions of interest.

The preferred embodiments may be used to expand the information obtainedfrom the markers, using either or both of examining the kinetics of themarkers over time and using several markers concurrently.

In order to increase the specificity of the test, additional secondsubstances (“secondary substances”), with reactivity andpharmaco-kinetics differing from those of the first substance can beused in order to enhance the differentiation between the differentpathologies, as explained above with respect to FIG. 134. The secondarysubstance, in this case thalium, ideally marks only a subset of thepopulation marked by the primary substance and does so at differentrates. Such a difference exists because of different affinity to variouscell types and different participation in metabolic reactions ofdifferent tissues. The difference is associated with the rate of markingand/or with the location of the marking.

Upon reading the radioactive signals emanating from the voxels stemmingfrom different substances at different time instances, it is possible tobuild for every voxel a multi dimensional data matrix S_(jk) whoseelements are intensity readings taken at instances K resulting from theinteraction of Substance J. Examination of every voxel of tissue in thismultidimensional space quantifies the temporal and specific reaction ofthe tissue to different substances and thus increases the probability ofspecific detection of different pathologies. Furthermore, standard imageprocessing techniques can be used in order to more accurately define thespatial location of different pathologies.

In addition to the method above, spatial properties that reflect typicalrelationships between neighboring voxels may also be a criteria andrepresented as part of the pattern of the tissue type.

Reference is now made to FIG. 135, which illustrates an additionalstatistical approach. In FIG. 135, an automatic algorithm based onexpected intensities may be used to determine if the entire organ orregion is diseased or non-diseased. Once it is possible to becometissue-aware, as explained above, then it is no longer necessary tocarry out such analysis on a voxel-by-voxel basis. Rather the system isable to determine where the organ lies say using a first marker and thena second marker may be imaged using the constraint of the organlocation, the second marker being able to locate the presence of thepathology.

Reference is now made to FIG. 136 that illustrates a method for usingthe tissue aware properties of the present embodiments in order to tunedetection to match tissue or organ emissivities. Generally, any region,no matter how much radiation it produces, can always be imagedsufficiently simply by leaving the measuring device in position for longenough. However, in many cases there may be limited time available. Forsuch cases in which there is limited time for data acquisition, thepresent embodiments can be used to identify regions that may be expectedto produce less emission. The system may then focus imaging resources orresolution onto those tissues according to the number of photonsavailable. Clearly the more photons obtained the more reliable is thedata, and therefore a tissue aware system is able to concentrate moredetectors on the weaker signaling tissues.

If there are still not enough photons, or there are not enoughdetectors, then another way of pooling resources is to merge neighboringvoxels (or regions). Such a procedure reduces resolution, but increasesthe overall number of photons for that merged region, and thus enablebetter classification of that region based on a more reliable photoncount. Such a compromise enables analysis of the same collected data byways that would allow high resolution where there are enough photons andlower resolutions where there are less photons, while maintainingreliability of the analysis.

Again the tissue regions may be identified using multiple markers.

The above-described embodiment may lead to controlled sensitivitylevels, currently not available with radioimaging.

The concept of using multiple antibodies can be used for therapypurposes, as in the following:

The specificity of a single antibody carrying a drug (or radioactivetherapy) determines the chance for non-target tissue to receive thedrug, and thus be subject to any toxicity of the drug. In cases wherethere are several antibodies, each with limited specificity, but withaffinity to different ‘background’ tissue, a combination of antibodiesmay be used to improve the overall specificity, and thus to reduceoverall toxicity and enable higher efficacy of treatment.

For example, a first antibody (A1) attached to a drug has an affinity(N1) to a first fold on a target tissue and a secondary affinity (B1)for a secondary non-target tissue. A second antibody (A2) attached to asimilar drug has an affinity (N2) to a second fold on the target tissueand an affinity (B2) for a different (tertiary) non-target tissue. Usinga therapy combining A1 and A2 enables better target vs. non-targetspecificity in which N1 and N2 both express affinities for the targettissue while B1 and B2 are dispersed between secondary and tertiarytissues.

In a more generalized embodiment, the system may include a signalanalysis module, including a library of patterns that are typical forevery cell type. Each type of cell has one or more patterns associatedwith it; the pattern determining how a set of markers, injectedaccording to a specific protocol (dosage, time, etc), is expressed inthat cell type. The analysis includes classification of the readingsfrom each voxel based on correlation, or other statistical tools forassessing the most probable tissue classification for each voxel.

Since there may be several cell types for a given disease (e.g. cancermay have several forms), the algorithm may be optimized to determine theexact tissue type per voxel or region. Alternatively, the algorithm maybe optimized to determine the general property of diseased/non-diseased,while taking the specific classification only as a factor in thestatistical analysis.

It should be noted that the system may allow for various protocols foradministering the markers, where injection of the various markers issimultaneous, or at multiple times, for example based upon the differentlifetime in the circulation.

The issue of generating imaging using two or more markers is nowconsidered mathematically.

An intensity distribution I, conventionally defined in terms ofradioactive emissions per seconds, is now redefined as a vector ofdistributions over the volume U, forming and input space. Each dimensionof the vector is distributions are different in each of theradiopharmaceuticals. The universal set U comprises a set of basicelements u (e.g., pixels in two dimensional spaces, voxels in threedimensional spaces), and I(u) is the intensity in a given basic elementuεU. For j radiopharmaceuticals this becomes I(u)^((j,t))

An inverse (or reconstruction) problem arises when one cannot sampledirectly from I, but can sample from a given set of views Φ. Aprojection φεΦ is defined by the set of probabilities {φ(u):uεU}, whereφ(u) is the probability of detecting a radioactive emission from a basicelement (pixel or voxel) u.

Projection φεΦ is further defined by viewing parameters, such as thephysical and geometrical properties of the detecting unit, attenuationparameters of the viewed volume U, and time parameters. Choosing a viewφεΦ, and then sampling according to the parameters of views Φ, yields anoptimal measurement.

For j radiopharmaceuticals or markers and k detectors, the probabilityof seeing a particle becomes φ_(j) ^(k)(u)

In the following analysis, I is the intensity of a radioactivesubstance, and the viewing parameters include the geometrical propertiesof a collimated detecting unit and the detecting unit's position andorientation with respect to volume U. The number of radioactiveemissions counted by the detecting unit within a time interval is aPoisson distribution, where φ(u) is the detection probability of aphoton emitted from voxel uεU and the mean of the distribution is theweighted sum Σ_(uεU)φ(u)I(u).

For the case of the kth detector a measurement Y_(k)=Σ_(uεU)X_(t)(u),where X(U) is a Poisson distribution.X _((j,k,t))(u)=I ^((i,t))(u)·φ(u)_(j) ^(k)(u).Where Y _((j,k,t)) =ΣX _((j,k,t))(u).Hence Y _((j,k,t)))=Poisson(Y _((j,k,t)))

The projection set is thus defined by a matrix Φ, whose rows are theprojections of the chosen views. I is a vector of densities (specifiedper each element in U), and ΦI is a vector of respective effectiveintensity levels for the views in the set. A vector of measurements y isobtained by a random sample from each view (according to the associatedPoisson distribution). As discussed above, there are various knownreconstruction methods that provide estimators for I given theprojections Φ and the measurements y.

Using the above mathematics the problem is solved (an image created) fora first vector say once an hour. The rates of change are determined.Simultaneously the problem is solved for another a second vector atsimilar time intervals and the new rates of change are determined. Thena stage of cross-identification is carried out between the two images,so that wanted tissues, as identified by each image minus unwantedtissues identified on each image, are concentrated, forming form a newimage. Cross-identification may be an iterative process.

In the example given above of the imaging of the heart using one bloodmarker and one muscular tissue marker, the areas identified by the bloodmarker are subtracted. The areas identified by the muscle marker areadded, and those tissues not identified by either are likewise ignoredas being signals from outside the target region.

The non-homogenous target area is typically a region of living tissue,generally belonging to a patient. The distinguishable regions within canbe different tissues, different organs, a mixture of blood and organtissue as with the above example of the heart, or tissue regionsexhibiting differential pathologies.

An alternative to the above described approaches for imaging using twoor more radiopharmaceuticals can be realized if one is able todistinguish between emissions of two or more radiopharmaceuticals byusing low doses of the radiopharmaceuticals which do not cause spectralinterference or masking (e.g. interference caused by Comptonscattering). For example, 20 mCi of Tc-99m produces numerous photons inthe tissue (due to Compton) that fall within the spectral line ofThallium (1-4 mCi). Reducing the Tc-99m dose to 2 or less mCi, resultsin minimal interference with Thallium, and enables simultaneous imagingof the two isotopes.

Use of novel low doses of Radiopharmaceuticals, typicallyRadiopharmaceuticals which result in less than 2.5 mrem EDE per Kg bodyweight (e.g., less than 2 mCi of Tc-99m) is enabled through the use ofmore sensitive emission detectors such as those described inPCT/IL2005/000394, PCT/IL2005/000572, PCT/IL2005/000575,PCT/IL2005/000394 and PCT/IL2005/000048, hereby included in theirentirety by reference.

Table 5 below provides typical prior art doses and novel low doses ofradiopharmaceuticals that are effectively imaged using the emissiondetection systems described in the above referenced PCT applications.

TABLE 5 radiopharmaceutical doses 55555 Dose utilized by Prior art dosein present invention Radiopharmaceutical Typical Purity in % mCi (range)mCi (range) Positron Emission Isotopes ISOTOPE/Half-Life Time Ammonia N13 9.96 min 20 0.05-5 Preferably - 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02,0.01 Fludeoxyglucose F-18 110 min 10 0.1-3 preferably - 3, 1, 0.1 SodiumFluoride F-18 110 min 0.1-3 preferably - 3, 1, 0.1 Methionine C-11 20.4min O-15 2.04 min Rubidium Rb-82 1.27 min Cu-62 9.8 min Ga-68 68.1 minProtein/peptide/antibody + Isotopes Indium-111 Capromab pendetide >90%(inject 5 0.01-2 (ProstaScint) after up to 8 hours Preferably - 2, 1,from mixing, 0.5, 0.1, 0.05, 0.01 isotope 1/2L ~72 hr) Indium In-111WBCs 0.5 0.001-0.2 (non-protein,peptide) Preferably - 0.2, 0.1, 0.05,0.01, 0.005, 0.001 Indium In-111 Satumomab Pendetide 5 0.01-2(OncoScint) Preferably - 2, 1, 0.5, 0.1, 0.05, 0.01 Technetium Tc 99mArcitumomab >60% (shelf life 20-30 0.05-5 (CEA-Scan) up to 4 hr/6 hrPreferably - 5, 2, 1, half-life) 0.5, 0.1, 0.05 Technetium Tc 99mFanolesomab 75-25 mcg of (Neutrospec) Fanolesomab is labeled with10-20mCi Technetium Tc 99m Nofetumomab Merpentan† Non-peptide/protein basedisotopes Cyanocobalamin Co 57 0.001 0.00001-0.0003 Preferably - 0.0003,0.0001, 0.00005, 0.00001 Ferrous Citrate Fe 59 Gallium Citrate Ga 67 50.01-1 10 for SPECT Preferably - 1, 0.5, 0.2, 0.1, 0.05, 0.01 Indium In111 Oxyquinoline Indium In 111 Pentetate Indium In 111 Pentetreotide 60.005-1 Preferably - 1, 0.5, 0.2, 0.1, 0.05, 0.01, 0.005 Iobenguane,Radioiodinated Iodohippurate Sodium I 123 Iodohippurate Sodium I 131IofetamineI 123 Iothalamate Sodium I 125 Krypton Kr 81m 10 (as a gas,0.05-2 USED FOR Preferably - 2, 1, DYNAMIC 0.5, 0.1, 0.05 IMAGING)Iodide 125 Albumin 0.02 0.0001-0.005 Preferably - 0.005, 0.002, 0.001,0.0005, 0.0001 Radioiodinated Albumin SodiumChromate Cr 51 0.150.001-0.05 0.1-0.3 Preferably - 0.05, 0.02, 0.01, 0.005, 0.001 SodiumIodide I 123 0.4, (also 0.1-0.2 0.001-0.05 as capsules) Preferably -0.1, 0.05, 0.02, 0.01, 0.005, 0.001 Also as capsules Sodium Iodide I 1310.004-0.01 0.00005-0.001 Preferably - 0.001, 0.0005, 0.0002, 0.0001,0.00005 (Sodium) Pertechnetate Tc 99m 10 0.01-5 100-200 micro forPreferably - 5, 2, 1, eye imaging (1 0.5, 0.2, 0.1, 0.05, drop per eye)0.02, 0.01 1mCi for cyctogram Technetium Tc 99m Albumin Technetium Tc99m Albumin NO LESS THAN 1-4 0.001-0.5 Aggregated 90% AT 2mCi in eachleg Preferably - 0.5, PREPARATION 0.2, 0.1, 0.05, 0.02, (Up to 6additional 0.01, 0.005, 0.002, hours on the shelf 0.001 turns it into45%), AS BEYOND A LEVEL IT MAY BLOCK LUNGS CAPILLARY - USED TO DETECTPULMONARY EMBOLISM DUE TO DVT Technetium Tc 99m Albumin ColloidTechnetium Tc 99m Erythrocytes 10-20 0.05-5 (RBCs) 20-25 for liverPreferably - 5, 2, 1, perfusion & 0.5, 0.2, 0.1, 0.05, SPECT 0.02, 0.01Technetium Tc 99m Depreotide 20 0.05-5 (NeoTect) Preferably - 5, 2, 1,0.5, 0.2, 0.1, 0.05 Technetium Tc 99m Apcitide 20 0.05-5 (AcuTect)Preferably - 5, 2, 1, 0.5, 0.2, 0.1, 0.05 TechnetiumTc 99m Bicisate(ECD, 20 0.05-5 Neurolite) Preferably - 5, 2, 1, 0.5, 0.2, 0.1, 0.05Technetium Tc 99m DMSA 2-6 (typically 5) 0.005-1 Dimercaptosuccinic acid(Succimer) Preferably - 1, 0.5, 0.2, 0.1, 0.05, 0.01, 0.005 TechnetiumTc 99m Disofenin 5 0.005-1 (HIDA) Preferably - 1, 0.5, 0.2, 0.1, 0.05,0.01, 0.005 TechnetiumTc 99m Exametazime 20 0.05-5 (HMPAO) Preferably -5, 2, 1, 0.5, 0.2, 0.1, 0.05 Technetium To 99m Gluceptate TechnetiumTc99m Lidofenin Technetium To 99m Mebrofenin 5mCi (non- jaundiced)8mCi(jaundiced) TechnetiumTc 99m Medronate 20 0.05-5 (MDP) 15 Preferably -5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.01 Technetium Tc 99m Mertiatide 5-100.005-1 (MAG3) Preferably - 1, 0.5, 0.2, 0.1, 0.05, 0.01, 0.005 ChromicPhosphate 4 0.05-1 Preferably - 1, 0.5, 0.2, 0.1, 0.05, 0.01 SR 89Chloride (Metastron) 4 (this is for 0.05-1 palliative Preferably - 1,0.5, treatment) 0.2, 0.1, 0.05, 0.01 Technetium Tc 99m OxidronateTechnetium Tc 99m Pentetate 3-5 (for GFR), 10-20 3 (brain/renal (DTPA)(for brain, renal perferred) 0.005-1 perfusion) Preferably - 1, 0.5,0.2, 0.1, 0.05, 0.02, 0.01, 0.005 TechnetiumTc 99m Pyrophosphate 150.005-5 20 for muscle Preferably - 5, 2, 1, necrosis 0.5, 0.3, 0.1,0.05, 0.02, 0.01, 0.005 Technetium Tc 99m (Pyro-and trimeta-) PhosphatesTechnetium Tc 99m Sestamibi 10-30 (typically 0.01-5 (Cardiolite,Miraluma - for breast 10 for rest and 30 preferably 5, 2, 1, imaging)for stress) 0.5, 0.2, 0.1, 0.05, 0.02, 0.01 Technetium Tc 99m SulfurColloid Technetium Tc 99m Teboroxime Technetium Tc 99m Tetrofosmin 5-33(typical 8-20) (MyoView) Technetium Tc 99m HDP 20-25 <30 years25-30.30yrs & obese Technetium Tc 99m Sulpher colloid 12mCi/70 kgThallous Chloride Ti 201 0.055 mCi/kg Xenon Xe 127 5-10 Xenon Xe 1335-10

Use of radiopharmaceutical cocktails yields generations of new products(premixed radiopharmaceutical pairs) and diagnostic procedures thatenable multi-dimensional, differential diagnosis and use of onediagnostic procedure for revealing any pathology. Radiopharmaceuticalcocktails also require significantly lower radiopharmaceutical dosageand results in several-fold increase in sensitivity as well as a 90%procedure time reduction and significant improvement in spatial andspectral resolution.

Radiopharmaceutical combinations are exemplified in a liver-spleen scanusing +RBC+gallium (for cases of liver SOL/hemangioma/abscess/hepatoma).Bone scan +gallium or bone scan +In-WBC (for osteomyelitis). Perfusionrest/stress+MIBG for autonomic system in heart, mapping+BMIPP for heartfailure with the addition of FDG for viability.

Assessment of the sentinel lymph node of tumors via Lymphoscintigraphy,(melanoma, breast, etc) with addition of FDG (and optionally MIBI) toassess the presence of tumor in these nodes (typically effected byperi-tumoral injection for lymphoscintigraphy and IV FDG). FIG. 139provides a table that further exemplifies nuclear scans which canbenefit from use of radiopharmaceutical cocktails and simultaneousimaging.

Although low doses are preferred for the reasons set forth hereinabove,higher doses can also be utilized in combinations provided one caneffectively isolate the signal resultant from each radiopharmaceutical.

One approach for signal isolation is detailed below. We denote theintensity density of isotope i in voxel u by I^(i)(u). Detector t,detects y_(tb) photons at energy bin b, detector t comprising acomposite of a collimator and a radiation sensor such as CZT, placed atsome location. In an actual system, a physical detector that takes snapshots from several locations is regarded as different detectors for thepurpose of the following derivations.

We denote by φ_(tb) ^(i)(u) the probability of a photon emitted fromisotope i in voxel u, to be detected by detector t at energy bin b. Thisprobability is determined by the geometrical and physical properties ofthe detector, its position, orientation, and the reduction of the energyof the photon emitted from isotope I, to the measured energy b. We willrefer to φ_(tb) ^(i)(u) as the functional in the following derivations.The functional can be either, analytically calculated via geometrytogether with applying the Compton Effect for scattering, measured viaexperiment, or partly calculated and tuned via experiment.

The change of angle θ of a photon emitted at energy E₀, and scattered toenergy E is given by:

${{E\left( {E_{0},\theta} \right)} = {\left. {E_{0}\left\lbrack \frac{m_{e}c^{2}}{{m_{e}c^{2}} + {E_{0}\left( {1 - {\cos(\theta)}} \right)}} \right\rbrack}\Leftrightarrow{\cos(\theta)} \right. = {1 - {\left( {\frac{1}{E} - \frac{1}{E_{0}}} \right)m_{e}c^{2}}}}},$

Where m_(e) represents the rest mass of the electron, and c is the speedof light in a vacuum.

The random count X_(tb) ^(i)(u) of photons that are emitted from voxel uand detected in measurement tb (detector t at energy bin b), is modeledby a Poisson process with mean Σ_(i)φ_(tb) ^(i)(u)I^(i)(u). The totalcount of photons detected in measurement tb is Y_(tb)=Σ_(u)X_(tb)(u),and the problem is to reconstruct the intensities I^(i)(u) from themeasurements y_(tb).

Simultaneous Submission of Multiple Isotopes

The measurements have a Poisson distributionY_(tb)˜Poiss(Σ_(i)Σ_(u)φ_(tb) ^(i)(u)I^(i)(u)).

The log-likelihood is given by:

${L\left( {{y/I^{1}},I^{2},K} \right)} = {{\sum\limits_{tb}{\ln\mspace{11mu}{{Poiss}\left( {y_{\;{tb}}/{\sum\limits_{i}{\sum\limits_{u}{\phi_{\;{tb}}^{\; i}(u){I^{\; i}(u)}}}}} \right)}}}=={\sum\limits_{tb}\left\{ {{- {\sum\limits_{i}{\sum\limits_{u}{{\phi_{tb}^{i}(u)}{I^{i}(u)}}}}} + {y_{tb}\mspace{11mu}{\ln\left\lbrack {\sum\limits_{i}{\sum\limits_{u}{{\phi_{tb}^{i}(u)}{I^{i}(u)}}}} \right\rbrack}} - {\ln\left( {y_{tb}!} \right)}} \right\}}}$

The maximum likelihood is the solution of set of non-linear equations:

${{\sum\limits_{tb}{\sum\limits_{u}{\phi_{tb}^{i}(u)}}} = {\sum\limits_{tb}\frac{\phi_{tb}^{i}y_{tb}}{{\hat{y}}_{tb}}}},{{for}\mspace{14mu}{all}\mspace{14mu} i}$${{where}\mspace{14mu}{\hat{y}}_{tb}} \equiv {\sum\limits_{i}{\sum\limits_{u}{{\phi_{tb}^{i}(u)}{{I^{i}(u)}.}}}}$

The solution may be solved via the EM approach:X _(tb) ^(i)(u)˜Poiss(φ_(tb) ^(i)(u)I ^(i)(u)).

The likelihood of the complete data:ln P(x/I ¹ ,I ² ,K)=Σ_(tb)Σ_(i)Σ_(u){−φ_(tb) ^(i)(u)I ^(i)(u)+x _(tb)^(i)(u)ln [φ_(tb) ^(i)(u)I ^(i)(u)]−ln(x _(tb) ^(i)(u)!)}

The EM based algorithm:

${{I^{i}(u)} = {\frac{1}{\sum\limits_{tb}{\phi_{tb}^{i}(u)}}{\sum\limits_{tb}{\frac{y_{tb}}{{\hat{y}}_{tb}}{\phi_{tb}^{i}(u)}{I^{i}(u)}}}}},{{for}\mspace{14mu}{all}\mspace{14mu} i}$${{where}\mspace{14mu}{\hat{y}}_{tb}} \equiv {\sum\limits_{i}{\sum\limits_{u}{{\phi_{tb}^{i}(u)}{{I^{i}(u)}.}}}}$

This is the basis for faster Ordered set based algorithms.

Two Separate Submissions of Two Isotopes—Two Step Estimation

We first submit isotope i=1, and scan. We estimate its densitydistribution I¹(u) using an EM based algorithm. Then we submit isotopei=2, while i=1 is still distributed in the volume. To estimate I²(u)given the estimated Î¹(u):

${{I^{2}(u)} = {\frac{1}{\sum\limits_{tb}{\phi_{tb}^{2}(u)}}{\sum\limits_{tb}{\frac{y_{tb}}{{\hat{y}}_{tb}}{\phi_{tb}^{2}(u)}{I^{2}(u)}}}}},{{{for}\mspace{14mu}{all}\mspace{14mu} i} = 2}$${{where}\mspace{14mu}{\hat{y}}_{tb}} \equiv {{\sum\limits_{u}{{\phi_{tb}^{2}(u)}{I^{2}(u)}}} + {\sum\limits_{u}{{\phi_{tb}^{1}(u)}{{{\hat{I}}^{1}(u)}.}}}}$

Extension to multiple submissions is straightforward.

2 Separate Submissions Two Isotopes—Combined Estimation

We first submit isotope i=1, and scan. We denote the measurements of thefirst scan by y_(tb) ⁽¹⁾.

We then submit isotope i=2, and scan. In this scan the two isotopes aredistributed. We denote the measurements of the first scan by y_(tb) ⁽²⁾.

We wish to estimate both distributions I¹(u) and I²(u) using themeasurements from both scans y_(tb) ⁽¹⁾ and y_(tb) ⁽²⁾.

We discriminate between the functionals of the first scan φ_(tb) ¹⁽¹⁾,and those of the second scan φ_(tb) ¹⁽²⁾, φ_(tb) ²⁽²⁾.

The measurements have the Poisson distributions:y _(tb) ⁽¹⁾˜Poiss(Σ_(u)φ_(tb) ¹⁽¹⁾(u)I ¹(u))y _(tb) ⁽²⁾˜Poiss(Σ_(u)φ_(tb) ¹⁽²⁾(u)I ¹(u)+φ_(tb) ²⁽²⁾(u)I ²(u))

The solution based on the EM approach:

${I^{1}(u)} = {\frac{1}{{\sum\limits_{tb}{\phi_{tb}^{1{(1)}}(u)}} + {\phi_{tb}^{1{(2)}}(u)} + {\phi_{tb}^{2{(2)}}(u)}}{\sum\limits_{tb}{\left( {\frac{y_{tb}^{(1)}{\phi_{tb}^{1{(1)}}(u)}}{{\hat{y}}_{tb}^{(1)}} + \frac{y_{tb}^{(2)}{\phi_{tb}^{1{(2)}}(u)}}{{\hat{y}}_{tb}^{(2)}}} \right){I^{1}(u)}}}}$${{I^{2}(u)} = {\frac{1}{{\sum\limits_{tb}{\phi_{tb}^{1{(1)}}(u)}} + {\phi_{tb}^{1{(2)}}(u)} + {\phi_{tb}^{2{(2)}}(u)}}{\sum\limits_{tb}{\left( \frac{y_{tb}^{(2)}{\phi_{tb}^{2{(2)}}(u)}}{{\hat{y}}_{tb}^{(2)}} \right){I^{2}(u)}}}}},{{{for}\mspace{14mu}{all}\mspace{14mu} i} = 2}$

Whereŷ _(tb) ⁽¹⁾≡Σ_(u)φ_(tb) ¹⁽¹⁾(u)I ¹(u)ŷ _(tb) ⁽²⁾Σ_(u)φ_(tb) ¹⁽²⁾(u)I ¹(u)+φ_(tb) ²⁽²⁾(u)I ²(u)

The above described algorithm enables identification of the differentenergy level photons (energy signature) emitted from a radioisotope(produced from directly collected photons as well as photons generatedfrom Compton scattering), or a plurality of radioisotopes (e.g.cocktail) administered to a body and detected by a scintillation camera.Thus, such an algorithm enables association between various energy levelphotons and an isotope source. In essence, this algorithm produces forevery radioisotope an energy signature that is composed of the variousenergy photons produced thereby in a body as a function of a voxelimaged by the camera.

The above-described algorithm can serve as a basis for more advancedimaging which enables specific tissue imaging by accounting for timedistribution of radiopharmaceuticals (especially radiotracers).

The prior art disclosed a plurality of radiotracers with varyingaffinities for various pathological or normal tissues. Table 5 aboveprovides several examples of such radiotracers. Each radiotracer ischaracterized by a unique distribution kinetics following administrationwith peak levels reached at specific time points in specific tissues. Bymonitoring distribution of each such radiotracer as a function of energyintensity emitted therefrom and a function of time; and by using theabove-described algorithm, one can associate each voxel imaged with atissue and a radiotracer signal signature.

Such association provides numerous benefits in imaging since theassociation enables identification of specific pathologies, confirmationof pathologies via multi-tracer comparison and use ofradiopharmaceuticals which include the same radioisotope attached to adifferent tracer.

It will be appreciated that time dependent distribution of radiotracerscan be generated on the fly or derived from data provided by themanufacturer. In any case, such data is used to correlate Voxel photonsto a tissue and radiotracer thereby enabling accurate imaging even incases where several radiotracers having the same isotope or in caseswhere Compton scattering of one radiotracer generates photons which arenaturally produced by another radiotracer.

Kinetics of radiotracer distribution and derivation of data from suchdistribution is exemplified by the following equation.

Suppose one tracer has uptake over time curve C1(t), and a second tracerhas uptake over the time-curve C2(t). Both use the same isotope (e.g.Tc-99m). If both are injected at the same time (or separate time dT),the reading will be:Reading(t)=A*C1(t)+B*C2(t−dT)

A and B relate to the response of the specific tissue location to thepresence of tracers 1 and 2 in the blood. C1 and C2 are known in theliterature as used for various body organs, in various injected doses,in various patient conditions (e.g. blood pressure, blood flow, . . . ),etc.

Therefore, a de-convolution process may enable separation of theReading(t) into its components A*C1(t) and b*C2(t), and A and Brepresent the tissue response.

By looking at the absolute values of A and B (compared with literature),their relative values (e.g. A/B), or their values vs. other organlocations, abnormalities can be detected.

Clearly, many more than just 2 tracers can be used, and injection doesnot have to be at once or at only two instances, but rather there may beany injection time plan P(t), and thus an expected level in the organ isa convolution of C1(t) with P1(t). The injection time plan is controlledand adjusted in response to the voxel readings, so as to emphasizespecific time points of interest.

For example, the time in which one radiotracer is expected to peak andthe other to diminish, etc. In particular, the injection time plan candetect the best timing to begin/increase/decrease/stop injections.

Another equation can be used to generate a tissue probability index foran imaged voxel as a function of time.Intensity(voxel)^((t))=Σ_(i) P _(i)(t)C _(i,k,n) ^((t))

Wherein:

P=injected dose

i=intensity

k=tissue type

n=state

C=function of tracer

(t)=time

Thus, C_(i,k,n) ^((t)) expression curve of a radiotracer ‘i’ in tissue‘k’ (e.g. heart, liver muscle blood) having a pathological state ‘n’(e.g. normal, ischemic, tumor, abnormal physiology, scar). C_(i) is avector that expresses the level of emission of each energy level of aradiotracer. It is possible that several tracers ‘i’ would produce thesame energy spectra lines, for example when different tracers are boundto the same isotope.

P can further depend on the location of injection, in case ofnon-systemic injection (e.g. in cases of direct organ injection).

C is typically provided by the tracer manufacturer or by researchersthat have mapped the uptake of the radiotracer in various tissues andpathologies. C may further be expressed by using a parametric model, forexample by using commonly acceptable bioavailability coefficients of thetracer; for example, uptake and clearance coefficients, interactioncoefficients and the like.

C can also be expressed in various patient populations (grouped bygender, age, medical history) and under various physiological conditions(rest, stress, stimulation, drugs).

The above described equation can be utilized to reconstruct the ‘k’ and‘n’ per voxel, which are most likely to match the reconstructed voxelintensity.

‘k’ and ‘n’ can also be constrained by prior knowledge, such asexpectation of presence of a specific type of tissue at a voxel orvoxels, and expected specific type of pathologies (prior knowledge of asuspected pathology). ‘k’ and ‘n’ can also be constrained by informationrelating to neighboring voxels or reference voxels which have beenpreviously determined, using for example, x-ray imaging.

Reconstruction of the bioavailability of a radiotracer for each voxelcan also be effected by reconstructing the kinetics of each tracer foreach voxel followed by matching the parameters rather than the timeseries of the intensities at each voxel.

Following the above described processing, the present system canrepresent data to the operator (for example a physician) as intensityover time, at each voxel, parametric representation (ratios betweendifferent radiotracers and the like which can be color coded) andfinally assigning a probability to the classification, e.g., 95% normal,3% typed pathology etc.

Reconstruction of the ‘k’, ‘n’ or the parametric representation of theCi may be utilized for further iteration and refinement of voxelintensity over time. It can be further improved and provide a method forthe direct recovery of the parametric representation or theclassification of a voxel (‘k’, ‘n’) without necessitating recovery ofthe voxel intensity over time. In this case, the kinetics equation areincorporated into the 3-D reconstruction model which is based uponcamera readings.

Table 6 below provides an example that illustrates the benefits ofassociating radiotracer information to generate a differential diagnosisthat cannot be derived from each radiotracer alone.

TABLE 6 differential diagnosis of heart ischemia using Thallium andmibiTc-99m Stress Post Late imaging Injection Rest injection stress(4-24 hrs) Thallium imaging mibiTc-99m imaging thallium Normal ++ ++ ++ischemic + NC ++ Scar (dead NC NC NC tissue) NC—no counts + low counts++ high counts

The table above illustrates the uptake profiles of normal ischemic andscar tissue using two separately injected and imagedradiopharmaceuticals, thallium and mibiTc-99m. Normal tissue and scartissue are easily differentiated since they present contrasting uptakeprofiles. Ischemic tissue however, shows low rest imaging counts andhigher counts 4-24 hours post injection for thallium, which indicatesthat this tissue is still capable of uptaking thallium over time andindicates possible loss of viability. However, post stress injection ofmibiTc-99m provides no counts for ischemic tissue, supporting the factthat that the tissue is ischemic, as normal tissue uptakes mibiTc-99m asefficiently as it does thallium.

FIGS. 138A-B illustrate simultaneous imaging of two differentco-injected radiopharmaceuticals, Tc-99m DMCA and Ga67 and Tc-99mSestamibi/Tc-99 mHDP and Ga67. In both cases anatomical imaging (CT, USor Echo) is concomitantly utilized in order to visualize the tissue. Asis illustrated by FIGS. 138A-B, use of the present invention enablesefficient co-imaging of both administered radiopharmaceuticals andaccurate differential diagnosis.

Thus, according to another aspect of the present invention there isprovided a system which enables time dependent analysis of voxelspectral information from one or more radioisotopes to thereby enablemore accurate tissue mapping and pathology diagnosis.

The system according to this aspect of the present invention performsthree main functions, acquisition of photons, association of each photonto a radioisotope source and a voxel as a function of time and imagereconstruction from voxels (association of each voxel to a tissue orpathology)

Thus, the system not only measures the accumulated level at a giventime, but also recovers kinetics parameter, thus enablingdifferentiation between multiple tracers. The differentiation isaccomplished (even if they have similar isotope) according to their timebehavior profile (which can be derived from, or verified against, theirprofile as generated by the manufacturer). Further, the differentiationis used to further verify the location of a voxel in the body andassociate other adjacent voxels to adjacent tissues and body regions.

Result of such imaging can denote probability of a diagnosis for a giventissue imaged and state of the tissue. For example, a single voxel, or acollection of voxels associated with a specific tissue region (e.g.heart) can be used to generate a probability of diagnosis as follows:87%—normal, 9%—ischemic, 3% scar, 1%—tumor; the probability beingderived from radioisotope mapping as a function of time and photonsignature and, additionally, as a function of radiotracer association.

Where a tissue is not known, a probability distribution can also begenerated. For example, blood pool imaging (by dynamic flow imaging) canhelp the algorithms know where blood is and where muscle is, thus thereconstruction algorithm described herein can take that into account bysubtracting from voxel maps of radiotracers which attach only to musclethe blood pool imaging maps.

A higher-level analysis determines disease diagnosis, not per voxel, butrather by providing to the system information on the disease and how itis typically manifested in patients. This embodiment of the presentsystem (which includes a large database) can support diagnosticdecision-making.

It will be appreciated that the availability of the informationdescribed above also enables tailoring of the exact injection profile(boluses, drips, etc) of each radiopharmaceutical.

In addition to the advantages described above (e.g. tissue mapping anddifferential diagnosis) use of radiopharmaceutical cocktails andsimultaneous dual imaging is also advantageous in that administration oftwo or more radiopharmaceuticals via a single injection shortens patientcycle time since there is now one imaging phase rather than two.

It is expected that during the life of this patent many relevantmarkers, radiological imaging devices and two and three dimensionalimaging systems will be developed and the scopes of the correspondingterms herein, are intended to include all such new technologies apriori.

Simplified Scatter Correction in the administration of Dual Isotopes

The present embodiment provides a method and apparatus for radioisotopethat address shortcomings of present radioisotope imaging from subjectscontaining two imaging isotopes. Specifically, the present inventionprovides methods, and gamma probes for two imaging isotopes, X1 and X2,wherein each isotope has a gamma energy, for example, Y1 and Y2,respectively; wherein the energy state of Y1 is greater than the energystate of Y2 and Y1 scatter interferes with measurements of Y2.

In accordance with embodiments of the present invention, imaging isperformed with fast gamma probes wherein two complete scans are taken,each is of a short duration, for example, 2-5 minutes.

In and exemplary embodiment, a radiopharmaceutical of X1 is administeredand an image of X1 is taken. The scatter at and around the region of Y2,ie., the cross talk of X1 at and around Y2, is obtained.

Following imaging X1, radiopharmaceutical of X2 is administered and animage of X1+X2 is taken. The scatter of X1 in the region of Y2, thecross talk of X1 at and around Y2, is then subtracted from the image ofX1+X2.

In an exemplary embodiment, Tl²⁰¹ and Tc^(99m) are administered in amyocardial perfusion study; Tc^(99m) having a photon emission at 140KeV, and Tl²⁰¹ having a photon emission energy 70 KeV; resulting incross talk around the 70 KeV region of Tl²⁰¹ photon emission.

In another exemplary embodiment, Tc^(99m) and In¹¹¹ are administered forpelvic SPECT imaging; Tl²⁰¹ having a photon emission energy 70 KeV asnoted above and In¹¹¹ has a photon emission of 170 KeV; resulting incross talk around the 140 KeV region of Tc^(99m) photon emission.

FIG. 140 is a flowchart 9400 for an imaging method of two isotopes, suchas X1 and X2, having distinct gamma energies, for example, Y1 and Y2,respectively. In an exemplary embodiment, the energy of Y1 is greaterthan the energy of Y2 and scatter from Y1 may interfere withmeasurements of Y2.

An imaging method 100 includes the following steps:

at 9402 radiopharmaceutical X1 is administered;

at 9404 a first shot duration image of X1 is obtained using a fast probeat and around the energy region of Y2;

at 9406 radiopharmaceutical X2 is administered while the patient remainsunder the imager;

at 9408, a second short duration image is obtained using a fast probe,the image including includes energy at and around Y1 and Y2; and

at 9410 the image of X1 at and around the energy region of Y2, (at 9404)is subtracted from the image of X1+X2 (at 9410) substantiallyeliminating cross talk of X1 from Y2.

Myocardial Perfusion

In an exemplary embodiment, the following procedure is used for imagingmyocardial perfusion:

A patient undergoes a stress test and is injected at peak exercise witha standard dose of Tc^(99m) sestamibi. The dose could be reduced due tothe high sensitivity of the DynaQ™ cardiac scanner thus minimizingscattered Tc^(99m) photons and patient radiation exposure.

After a recovery of approximately 60 minutes, the patient is positionedunder a DynaQ™ Cardiac or DynaQ™ CVCT Scanner. A brief pre-scan image ofthe Tc^(99m) sestamibi distribution is obtained at and around 70 KeV; anenergy associated with imaging of Tl²⁰¹. This scan is typicallyperformed in under 2 minutes due to the sensitivity of the DynaQ™scanner and is used to subtract Tc^(99m) sestamibi cross-talk from theTl²⁰¹ energy window in final image processing. While still under theDynaQ™ scanner, the patient is injected with a standard dose of Tl²⁰¹.

Simultaneous dual isotope data is then acquired, typically in less than3 minutes. Utilization of the above-noted Tc^(99m) sestamibi scan,herein a “pre-scan”, the resultant image can be resolved on a pixel bypixel basis. Execution of the pre-scan image is enabled by the rapidacquisition of the DynaQ™ system, for example, as taught by commonlyowned PCT/IL2005/000575, hereby incorporated in its entirety byreference.

It will be appreciated that the procedure would not be practical inabsence of the high speed of the DynaQ™ scanner.

It will be appreciated that similar performance can be achievedsubstituting one or more isotopes for Tc^(99m) sestamibi and/or Tl²⁰¹,providing that the speed of acquisition is much higher than today'sstandard.

Referring further to the drawings, FIG. 141 schematically represents atime line for myocardial perfusion, in accordance with embodiments ofthe present invention.

Accordingly, at time zero, the patient begins physical exercise,represented as A. The exercise optionally lasts 10-15 minutes, and afterabout 7 minutes Tc^(99m) is administered, for example, by injection. Thepatient continues to exercise 1-3 minutes longer.

At 50 to 60 minutes later, a Tc^(99m) scan, lasting about 2-3 minutes,is obtained.

Preferably, while the patient remains under the scanner, Tl²⁰¹ isadministered, for example, by injection.

Some 2-3 minutes after the second administration, a dual isotope scan,also lasting about 2-3 minutes is obtained.

Referring further to the drawings, FIGS. 142 a-142 c are schematicrepresentations of a Tc^(99m) photopeak (FIG. 142 a), a Tl²⁰¹ photopeak(FIG. 142 b), and Tc^(99m) cross talk contribution to at and around theTl²⁰¹ main energy window (FIG. 142 c).

Pelvic Scans

In accordance with a second example, the DynaQ system is used forobtaining a pelvic SPECT, in two scans of rapid acquisitions, asfollows:

i. administering In¹¹¹, having an energy of 170 Kev gamma;

ii. allowing distribution of In¹¹¹ and performing a first scan for theIn¹¹¹ at and around the 140 KeV energy window of Tc^(99m),

iii. administering the Tc^(99m), of 140 Kev gamma;

iv. allowing distribution of Tc^(99m) and performing a second scan ofboth Tc^(99m) and In¹¹¹; and

v. subtracting the cross talk of In¹¹¹ at and around the 140 KeV energywindow of Tc^(99m) from the second scan of both Tc^(99m) and In¹¹¹,

wherein both the first and second scans are of short durations of about2-4 minutes each.

The present embodiment is possible with a fast gamma camera, for exampleas taught by the present invention.

The aforementioned description is based on Okudan B, Smitherman T C. Thevalue and throughput of rest Thallium-201/stress Technetium-99msestamibi dual-isotope myocardial SPECT. Anadolu Kardiyol Derg. 2004June; 4(2):161-8; Weinmann P, Faraggi M, Moretti J L, Hannequin P.Clinical validation of simultaneous dual-isotope myocardialscintigraphy. Eur J Nucl Med Mol. Imaging. 2003 January; 30(1):25-31;Hannequin P, Weimann P, Mas J, Vinot S. Preliminary clinical results ofphoton energy recovery in simultaneous rest Tl-201/stress Tc-99msestamibi myocardial SPECT. J Nucl Cardiol. 2001 March-April;8(2):144-51; Unlu M, Gunaydin S, Ilgin N, Inanir S, Gokcora N, Gokgoz L.Dual isotope myocardial perfusion SPECT in the detection of coronaryartery disease: comparison of separate and simultaneous acquisitionprotocols. J Nucl Biol Med. 1993 December; 37(4):233-7; Lowe V J, GreerK L, Hanson M W, Jaszczak R J, Coleman R E. Cardiac phantom evaluationof simultaneously acquired dual-isotope rest thallium-201/stresstechnetium-99m SPECT images. J Nucl Med. 1993 November;34(11):1998-2006; Knesaurek K, Machac J. Comparison of correctiontechniques for simultaneous 201Tl/99mTc myocardial perfusion SPECTimaging: a dog study. Phys Med. Biol. 2000 November; 45(11):N167-76;Yang D C, Ragasa E, Gould L, Huang M, Reddy C V, Saul B, Schifter D,Rainaldi D, Feld C, Tank R A. Radionuclide simultaneous dual-isotopestress myocardial perfusion study using the “three window technique”.Clin Nucl Med. 1993 October; 18(10):852-7; Nakamura M, Takeda K,Ichihara T, Motomura N, Shimizu H, Saito Y, Nomura Y, Isaka N, KonishiT, Nakano T. Feasibility of simultaneous stress 99 mTc-sestamibi/rest201Tl dual-isotope myocardial perfusion SPECT in the detection ofcoronary artery disease. J Nucl Med. 1999 June; 40(6):895-903; andHannequin P, Mas J, Germano G. Photon energy recovery for crosstalkcorrection in simultaneous 99 mTc/201Tl imaging. J Nucl Med. 2000 April;41(4):728-36.

Diagnostic Protocols

Protocols for Fast Cardiac Imaging

The following cardiac imaging protocols include two imaging stages, atrest and after stress. Generally, they are performed with gating andattenuation corrections, as illustrated in the Tables of FIGS. 148A-V.

1. A fast, dual-isotope, imaging protocol: For imaging at rest, apatient is injected with about 3 mCi of Th-201-thallous chloride, sometime prior to the imaging, while remaining substantially at rest. Aftera waiting period of 10-15 minutes, a rest imaging of about 2 minutes istaken. The patient is then subject to a physical stress, for example byexercising on a treadmill. At the peak stress level, the patient isinjected with about 20-30 mCi of Tc-99m-sestamibi. After a waitingperiod of about 30-60 minutes, during which the patient is advised toremain in motion, for example, by walking, a post-stress imaging ofabout 2 minutes is taken. The total imaging time of this protocol isabout 4 minutes, and the total patient time is about 60-90 minutes. Theadvantage of this protocol is in the fast imaging time, of about 2minutes per image, when compared to standard imaging methods.

2. A fast, single-isotope, imaging protocol: For imaging at rest, thepatient is injected with about 8-10 mCi of Tc-99m-sestamibi, some timeprior to the imaging, while remaining substantially at rest. After awaiting period of about 30 minutes, a rest imaging of about 2 minutes istaken. The patient is then subject to a physical stress, for example byexercising on a treadmill. At the peak stress level, the patient isinjected with about 20-30 mCi of Tc-99m-sestamibi. After a waitingperiod of about 30-60 minutes, during which the patient is advised toremain in motion, for example, by walking, a post-stress imaging ofabout 2 minutes is taken. The total imaging time of this protocol isabout 4 minutes, and the total patient time is about 60-90 minutes. Theadvantage of this protocol is in the fast imaging time, of about 2minutes per image, when compared to standard imaging methods.

3. An ultra fast, dual-isotope, imaging protocol: For imaging at rest,the patient is injected with about 3 mCi of Th-201-thallous chloride,some time prior to the imaging, while remaining substantially at rest.After a waiting period of about 2 minutes, a rest imaging of about 2minutes is taken. The patient is then subject to a pharmacologicalstress, for example, for example, by the administration of adenosine. Atthe peak stress level, the patient is injected with about 20-30 mCi ofTc-99m-sestamibi, while positioned under the camera. Substantiallyimmediately after the second injection, a post-stress imaging of about 2minutes is taken. The total imaging time of this protocol is about 4minutes, and the total patient time is about 20-30 minutes. Theadvantage of this protocol is in the fast imaging time, of about twominutes, and in the avoidance of liver radioactivity, since imagingtakes place substantially immediately after injection, before buildup ofradioactivity in the liver takes place.

4. An ultra fast, single-isotope, imaging protocol: For imaging at rest,the patient is injected with about 8-10 mCi of Tc-99m-sestamibi, sometime prior to the imaging, while remaining substantially at rest. Aftera waiting period of about 0-2 minutes, a rest imaging of about 2 minutesis taken. The patient is then subject to a pharmacological stress, forexample, by the administration of adenosine. At the peak stress level,the patient is injected with about 20-30 mCi of Tc-99m-sestamibi, whilepositioned under the camera. Substantially immediately after the secondinjection, a post-stress imaging of about 2 minutes is taken. The totalimaging time of this protocol is about 4 minutes, and the total patienttime is about 20-30 minutes. The advantage of this protocol is in thefast imaging time, of about two minutes, and in the avoidance of liverradioactivity, as in protocol 3.

5. A dual-isotope, simultaneous imaging protocol: The patient isinjected with about 3 mCi of Th-201-thallous chloride, and proceeds to atreadmill. At the peak stress level, the patient is injected with about20-30 mCi of Tc-99m-sestamibi. After a waiting period of about 30-60minutes, during which the patient is advised to remain in motion, forexample, by walking, a simultaneous imaging of about 2 minutes is taken.The total imaging time of this protocol is about 2 minutes, and thetotal patient time is about 40-90 minutes. The advantage of thisprotocol is in the fast imaging time, of about 2 minutes of singleacquisition, and more important, in the dual registration of the twoisotopes, when imaged simultaneously.

6. A fast, dual-isotope, thallium-stress-perfusion, imaging protocol:For imaging at rest, the patient is injected with about 3 mCi ofTc-99m-sestamibi, some time prior to the imaging, while remainingsubstantially at rest. After a waiting period of about 30 minutes, arest imaging of about 2 minutes is taken. The patient is then subject toa physical stress, for example by exercising on a treadmill. At the peakstress level, the patient is injected with about 3 mCi ofTh-201-thallous chloride. After a waiting period of about 10-15 minutes,during which the patient is advised to remain in motion, for example, bywalking, a post-stress imaging of about 4 minutes is taken. The totalimaging time of this protocol is about 6 minutes, and the total patienttime is about 45-60 minutes. The advantage of this protocol is in thefast imaging time, of about 2-4 minutes per image, and in the betterflow linearity, the ability to detect small lesions, and the relativelyhigh viability.

7. A fast, dual-isotope, thallium-stress-perfusion, imaging protocol:For imaging at rest, the patient is injected with about 3 mCi ofTc-99m-sestamibi, some time prior to the imaging, while remainingsubstantially at rest. After a waiting period of about 30 minutes, arest imaging of about 2 minutes is taken. The patient is then subject toa pharmacological stress, for example, by the administration ofadenosine. At the peak stress level, the patient is injected with about3 mCi of Th-201-thallous chloride, while positioned under the camera.Substantially immediately after the second injection, a post-stressimaging of about 4 minutes is taken. The total imaging time of thisprotocol is about 6 minutes, and the total patient time is about 20-30minutes. The advantage of this protocol is in the fast imaging time, ofabout 6 minutes per image, and in the better flow linearity, the abilityto detect small lesions, and the relatively high viability.

8. An ultra fast, dual-isotope, thallium-stress-perfusion, imagingprotocol: For imaging at rest, the patient is injected with about 3 mCiof Tc-99m-sestamibi, and rest imaging of about 2 minutes is taken, withsubstantially no waiting period. The patient is then subject to apharmacological stress, for example, by the administration of adenosine.At the peak stress level, the patient is injected with about 3 mCi ofTh-201-thallous chloride, while positioned under the camera.Substantially immediately after the second injection, a post-stressimaging of about 4 minutes is taken. The total imaging time of thisprotocol is about 6 minutes, and the total patient time is about 10-20minutes. The advantage of this protocol is in the fast imaging time, ofabout 6 minutes per image, in the better flow linearity, the ability todetect small lesions, the relatively high viability, the singleacquisition, and more important, the dual registration of the twoisotopes, when imaged simultaneously.

9. A fast, dual-isotope, simultaneous imaging protocol: For imaging atrest, the patient is injected with about 3 mCi of Tc-99m-sestamibi, sometime prior to the imaging, while remaining substantially at rest. Aftera waiting period of about 30 minutes, a rest imaging of about 2 minutesis taken. The patient is then subject to a pharmacological stress, forexample, by the administration of adenosine. At the peak stress level,the patient is injected with about 3 mCi of Th-201-thallous chloride.After a waiting period of about 2 minutes, a post-stress imaging ofabout 4 minutes is taken. The total imaging time of this protocol isabout 6 minutes, and the total patient time is about 10-20 minutes. Theadvantage of this protocol is in the single imaging time, of about 6minutes per image, and in the better flow linearity, the ability todetect small lesions, and the relatively high viability.

10. A fast, single-isotope, Tc-99m-teboroxime imaging protocol: Forimaging at rest, a patient is injected with about 8-10 mCi ofTc-99m-teboroxime, while the patient is under the camera, and a restimaging of about 10 minutes is taken. The patient is then subject to apharmacological stress, for example, by the administration of adenosine.At the peak stress level, the patient is injected with about 20-30 mCiof teboroxime, while positioned under the camera. Substantiallyimmediately after the second injection, a post-stress imaging of about 2minutes is taken. The total imaging time of this protocol is about 12minutes, and the total patient time is about 20 minutes.

Protocols for Fast General Imaging

The following fast imaging protocols are illustrated in Tables of FIGS.148A-V.

11. Lung V/P-DTPA aerosol and macro-aggregated albumin (lung perfusionagent) protocol, for studying lung perfusion by quantitative parameters,such as ml/min/gr. A patient is injected with Tc-99m-diethylene triaminepentaacetate (DTPA), up to about 5mCi (up to 1M particles)Tc-99m-macro-aggregated albumin (MAA), I-123 while positioned under thecamera. Substantially immediately after injection, an imaging of up toabout 6 minutes is taken, with an energy window of between 3 and 15%.The advantage of this protocol is that it is fast.

12. Fast MDP-bone scan-whole body scan protocol, routinely performed tolook for

bone tumors or inflammatory processes of the bone (e.g. osteomyelitis),with an acquisition time of up to 6 minutes, using Tc-99m-MDP, at20-30mCi total dose, with a waiting period of 0-60 minutes, energywindow—anywhere between 3-15%, advantage—fast.

Protocols for Low-Dose Cardiac Imaging

The following cardiac imaging protocols include two imaging stages, atrest and after stress. Generally, they are performed with gating andattenuation corrections, as illustrated in the Tables of FIGS. 148A-V.

14. A low-dose, dual-isotope, imaging protocol: For imaging at rest, apatient is injected with about 0.3 mCi of Th-201-thallous chloride, sometime prior to the imaging, while remaining substantially at rest. Aftera waiting period of 10-15 minutes, a rest imaging of about 15 minutes istaken. The patient is then subject to a physical stress, for example byexercising on a treadmill. At the peak stress level, the patient isinjected with about 3 mCi of Tc-99m-sestamibi. After a waiting period ofabout 30-60 minutes, during which the patient is advised to remain inmotion, for example, by walking, a post-stress imaging of about 15minutes is taken. The total imaging time of this protocol is about 25-30minutes, and the total patient time is about 90 minutes. The energywindow is between 3 and 15%. The advantage of this protocol is in thelow dose, and the better spectral resolution that results from it.

15. A low-dose, single-isotope, imaging protocol: For imaging at rest, apatient is injected with about 0.3 mCi of Tc-99m-sestamibi, some timeprior to the imaging, while remaining substantially at rest. After awaiting period of about 30 minutes, a rest imaging of about 15 minutesis taken. The patient is then subject to a physical stress, for exampleby exercising on a treadmill. At the peak stress level, the patient isinjected with about 3 mCi of Tc-99m-sestamibi. After a waiting period ofabout 30-60 minutes, during which the patient is advised to remain inmotion, for example, by walking, a post-stress imaging of about 15minutes is taken. The total imaging time of this protocol is about 25-30minutes, and the total patient time is about 90 minutes. The energywindow is between 3 and 15%. The advantage of this protocol is in thelow dose, and the better spectral resolution that results from it.

16. A low-dose, dual-isotope, simultaneous imaging protocol: The patientis injected with about 0.3 mCi of Th-201-thallous chloride and thensubject to a physical stress, for example by exercising on a treadmill.At the peak stress level, the patient is injected with about 3-5 mCi ofTc-99m-sestamibi. After a waiting period of about 30-60 minutes, duringwhich the patient is advised to remain in motion, for example, bywalking, a simultaneous rest and post-stress imaging of about 5-15minutes is taken. The total imaging time of this protocol is about 20-30minutes, and the total patient time is about 90 minutes. The energywindow is between 3 and 15%. The advantage of this protocol is in thelow dose, better image registration, and better spectral resolution.

17. A low-dose, dual-isotope, fast imaging protocol: For imaging atrest, the patient is injected with about 0.3 mCi of Th-201-thallouschloride, while under the camera. After a waiting period of about 2minutes, a rest imaging of about 15 minutes is taken. The patient isthen subject to a pharmacological stress, for example, by theadministration of adenosine. At the peak stress level, the patient isinjected with about 20-30 mCi of Tc-99m-sestamibi, while under thecamera, and a post-stress imaging of about 2 minutes is taken,immediately. The total imaging time of this protocol is about 17minutes, and the total patient time is about 45 minutes. The energywindow is about 3-15%. The advantage of this protocol is that it isfast, and low dose.

18. A low-dose, single-isotope, fast imaging protocol: For imaging atrest, the patient is injected with about 0.3 mCi of Tc-99m-sestamibi,while under the camera. Immediately, a rest imaging of about 15 minutesis taken. The patient is then subject to a pharmacological stress, forexample, by the administration of adenosine. At the peak stress level,the patient is injected with about 3 mCi of Tc-99m-sestamibi, whileunder the camera, and a post-stress imaging of about 15 minutes istaken, immediately. The total imaging time of this protocol is about 30minutes, and the total patient time is about 45 minutes. The energywindow is about 3-15%. The advantage of this protocol is that it isfast, and low dose.

Protocols for Low-Dose General Imaging

The following low-dose imaging protocols are illustrated in the Tablesof FIGS. 148A-V.

19. Brain perfusion mapping protocol: used for mapping of perfusiondescribed by quantitative parameters (mg/min/gr); measurement ofcerebral flow reserve in stress protocols using pharmacological stressagents; parametric quantitation; and identification of diseasesignature, for example in Alzheimer's, depression, schizophrenia, andsimilar conditions. A patient is injected with up to about 20 mCiTc-99m-exametazine (HMPAO), up to about 20 mCi Tc-99mN,N′(1,2-ethlenediyl)bis-L-cysteine diethyl ester (Tc-99m-ECD), and upto about 5 mCi of 1-123 iofetamine hydrochloride. After a waiting periodof up to one hour, imaging is taken, with an energy window of between 3and 15%. The advantage of this protocol is that it can show stroke at anearly stage.

20. Hepatobiliary imaging: for studying the structure of the liver,including identification of hemangiomas, abcesses, and liverenlargement. A patient is injected with up to about 0.5 mCiTc-99m-mebrofenin while under the camera, and imaging is begunimmediately. The acquisition time is up to about 30 minutes, with anenergy window of between 3 and 15%. This protocol studies fluid flow,rate of tracer uptake (passive or active), accumulation andredistribution of tracer, tracer metabolism, and secretion and/orwashout of tracer or metabolite (passive or active).

21. Lung V/P-DTPA aerosol and macro-aggregated albumin (lung perfusionagent) protocol, for studying lung perfusion by quantitative parameters,such as ml/min/gr. A patient is injected with Tc-99m-diethylene triaminepentaacetate (DTPA), up to about 5mCi (up to 1M particles)Tc-99m-macro-aggregated albumin (MAA), I-123 while positioned under thecamera. Substantially immediately after injection, an imaging of up toabout 6 minutes is taken, with an energy window of between 3 and 15%.The advantage of this protocol is that it is fast.

Protocols for Imaging of Dynamic Processes

22. Cardiac perfusion (thallium rest) protocol: this protocol is usedfor imaging of cardiac perfusion under rest conditions. The perfusion isdescribed by quantitative parameters (ml/min/gr), coronary flow reserveand parametric quantitation. A patient is injected with up to about 4mCi Tl-201 thallous chloride, with the camera running, and imaging isbegun immediately. Imaging is taken for a time of from about 2 to about20 minutes, with an energy window of between 3 and 15%. This protocolenables the study of fluid flow, rate of tracer uptake (passive oractive), tracer accumulation and redistribution, tracer metabolism, andsecretion and/or washout (active or passive) of tracer/metabolites.

23. Cardiac perfusion (thallium stress) protocol: this protocol is usedfor imaging of cardiac perfusion under stress conditions. The perfusionis described by quantitative parameters (ml/min/gr), coronary flowreserve and parametric quantitation. A patient subjected to apharmacological stress, for example, for example, by the administrationof adenosine or to a physical stress, for example by exercising on atreadmill. At the peak stress level, the patient is injected with up toabout 4 mCi Tl-201 thallous chloride, with the camera running, andimaging is begun immediately. Imaging is taken for a time of from about2 to about 20 minutes, with an energy window of between 3 and 15%. Thisprotocol enables the study of fluid flow, rate of tracer uptake (passiveor active), tracer accumulation and redistribution, tracer metabolism,and secretion and/or washout (active or passive) of tracer/metabolites.

24. Cardiac perfusion (teboroxime rest) protocol: this protocol is usedfor imaging of cardiac perfusion under rest conditions. The perfusion isdescribed by quantitative parameters (ml/min/gr), coronary flow reserveand parametric quantitation. A patient is injected with up to about 30mCi teboroxime, with the camera running, and imaging is begunimmediately. Imaging is taken for a time of up to 15 minutes, with anenergy window of between 3 and 15%. This protocol enables the study offluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

25. Cardiac perfusion (teboroxime stress) protocol: this protocol isused for imaging of cardiac perfusion under stress conditions. Theperfusion is described by quantitative parameters (ml/min/gr), coronaryflow reserve and parametric quantitation. A patient subjected to apharmacological stress, for example, for example, by the administrationof adenosine or to a physical stress, for example by exercising on atreadmill. At the peak stress level, the patient is injected with up toabout 4 mCi teboroxime, with the camera running, and imaging is begunimmediately. Imaging is taken for a time of up to 15 minutes, with anenergy window of between 3 and 15%. This protocol enables the study offluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

26. Cardiac perfusion (sestamibi rest) protocol: this protocol is usedfor imaging of cardiac perfusion under rest conditions. The perfusion isdescribed by quantitative parameters (ml/min/gr), coronary flow reserveand parametric quantitation. A patient is injected with up to about 30mCi Tc-99m-sestamibi, with the camera running, and imaging is begunimmediately. Imaging is taken for a time of up to 15 minutes, with anenergy window of between 3 and 15%. This protocol enables the study offluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

27. Cardiac perfusion (sestamibi stress) protocol: this protocol is usedfor imaging of cardiac perfusion under stress conditions. The perfusionis described by quantitative parameters (ml/min/gr), coronary flowreserve and parametric quantitation. A patient subjected to apharmacological stress, for example, for example, by the administrationof adenosine or to a physical stress, for example by exercising on atreadmill. At the peak stress level, the patient is injected with up toabout 30 mCi Tc-99m-sestamibi, with the camera running, and imaging isbegun immediately. Imaging is taken for a time of up to 15 minutes, withan energy window of between 3 and 15%. This protocol enables the studyof fluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

28. Cardiac perfusion (tetrofosmin rest) protocol: this protocol is usedfor imaging of cardiac perfusion under rest conditions. The perfusion isdescribed by quantitative parameters (ml/min/gr), coronary flow reserveand parametric quantitation. A patient is injected with up to about 30mCi tetrofosmin, with the camera running, and imaging is begunimmediately. Imaging is taken for a time of up to 15 minutes, with anenergy window of between 3 and 15%. This protocol enables the study offluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

29. Cardiac perfusion (tetrofosmin stress) protocol: this protocol isused for imaging of cardiac perfusion under stress conditions. Theperfusion is described by quantitative parameters (ml/min/gr), coronaryflow reserve and parametric quantitation. A patient subjected to apharmacological stress, for example, for example, by the administrationof adenosine or to a physical stress, for example by exercising on atreadmill. At the peak stress level, the patient is injected with up toabout 30 mCi tetrofosmin, with the camera running, and imaging is begunimmediately. Imaging is taken for a time of up to 15 minutes, with anenergy window of between 3 and 15%. This protocol enables the study offluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

30. Cardiac perfusion (Q12 NAME FROM SHANKAR rest) protocol: thisprotocol is used for imaging of cardiac perfusion under rest conditions.The perfusion is described by quantitative parameters (ml/min/gr),coronary flow reserve and parametric quantitation. A patient is injectedwith up to about 30 mCi Tc-99m-sestamibi, with the camera running, andimaging is begun immediately. Imaging is taken for a time of up to 15minutes, with an energy window of between 3 and 15%. This protocolenables the study of fluid flow, rate of tracer uptake (passive oractive), tracer accumulation and redistribution, tracer metabolism, andsecretion and/or washout (active or passive) of tracer/metabolites.

31. Cardiac perfusion (Q12 NAME FROM SHANKAR stress) protocol: thisprotocol is used for imaging of cardiac perfusion under stressconditions. The perfusion is described by quantitative parameters(ml/min/gr), coronary flow reserve and parametric quantitation. Apatient subjected to a pharmacological stress, for example, for example,by the administration of adenosine or to a physical stress, for exampleby exercising on a treadmill. At the peak stress level, the patient isinjected with up to about 30 mCi Tc-99m-sestamibi, with the camerarunning, and imaging is begun immediately. Imaging is taken for a timeof up to 15 minutes, with an energy window of between 3 and 15%. Thisprotocol enables the study of fluid flow, rate of tracer uptake (passiveor active), tracer accumulation and redistribution, tracer metabolism,and secretion and/or washout (active or passive) of tracer/metabolites.

32. BMIPP (rest) protocol: this protocol is used for imaging of cardiacperfusion under rest conditions. The perfusion is described byquantitative parameters (ml/min/gr), coronary flow reserve andparametric quantitation. A patient is injected with up to about 30 mCiTc-99m-sestamibi, with the camera running, and imaging is begunimmediately. Imaging is taken for a time of up to 5 minutes, with anenergy window of between 3 and 15%. This protocol enables the study offluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

33. BMIPP (stress) protocol: this protocol is used for imaging ofcardiac perfusion under stress conditions. The perfusion is described byquantitative parameters (ml/min/gr), coronary flow reserve andparametric quantitation. A patient subjected to a pharmacologicalstress, for example, for example, by the administration of adenosine orto a physical stress, for example by exercising on a treadmill. At thepeak stress level, the patient is injected with up to about 30 mCiTc-99m-sestamibi, with the camera running, and imaging is begunimmediately. Imaging is taken for a time of up to 5 minutes, with anenergy window of between 3 and 15%. This protocol enables the study offluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

34. A protocol utilizing any of the above combinations: this protocol isused for imaging of cardiac perfusion under either stress or restconditions. The perfusion is described by quantitative parameters(ml/min/gr), coronary flow reserve and parametric quantitation. Apatient is injected with any of the above radiopharmaceuticals, with thecamera running, and imaging is begun immediately. Imaging is taken for atime of up to 10 minutes, with an energy window of between 3 and 15%.This protocol enables the study of fluid flow, rate of tracer uptake(passive or active), tracer accumulation and redistribution, tracermetabolism, and secretion and/or washout (active or passive) oftracer/metabolites.

35. A protocol utilizing all PET radiopharmaceuticals within thecurrently used PET protocols used with our SPECT camera: this protocolis used for imaging of cardiac perfusion under stress or restconditions. The perfusion is described by quantitative parameters(ml/min/gr), coronary flow reserve and parametric quantitation. Apatient is injected with any PET radiopharmaceutical, as discussedabove, with the camera running, and imaging is begun immediately.Imaging is taken for a time of up to 15 minutes, with an energy windowof between 3 and 15%. This protocol enables the study of fluid flow,rate of tracer uptake (passive or active), tracer accumulation andredistribution, tracer metabolism, and secretion and/or washout (activeor passive) of tracer/metabolites.

36. Cancer—tumor perfusion protocol—evaluation of tumors by singleisotope (need to expand on the breast) SPECT with Teboroxime TC-99m orTc-99m-sestamibi: this protocol is used for imaging of cardiac perfusionunder rest or stress conditions. Image tumor blood supply with Tl-201thallous chloride in combination with Tc-99m-sestamibi uptake andwashout which is affected by the MDR complex showing therapeuticresponse to chemo. The perfusion is described by quantitative parameters(ml/min/gr) and parametric quantitation. A patient is injected with upto about 30 mCi Tc-99m-sestamibi, with the camera running, and imagingis begun immediately. Imaging is taken for a time of up to 5 minutes,with an energy window of between 3 and 15%. This protocol enables thestudy of fluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

37. Cancer—tumor perfusion protocol—evaluation of tumors by simultaneousdual isotope SPECT with Tl-201 thallous chloride and Tc-99m-sestamibi:this protocol is used for imaging of cardiac perfusion under rest orstress conditions. Tumor imaging; Image tumor blood supply with Tl-201thallous chloride in combination with Tc-99m-sestamibi washout which isaffected by the MDR complex showing therapeutic response to chemo. Theperfusion is described by quantitative parameters (ml/min/gr) andparametric quantitation. A patient subjected to a pharmacologicalstress, for example, for example, by the administration of adenosine orphysical stress, for example by exercising on a treadmill. At the peakstress level, the patient is injected, simultaneously, with up to about4 mCi Tl-201 thallous chloride and up to 30 mCi Tc-99m-sestamibi, withthe camera running, and imaging is begun immediately. Imaging is takenfor a time of up to 5 minutes, with an energy window of between 3 and15%. This protocol enables the study of fluid flow, rate of traceruptake (passive or active), tracer accumulation and redistribution,tracer metabolism, and secretion and/or washout (active or passive) oftracer/metabolites.

38. Kidney—renal function (111-In-DTPA and oomTc-MAG3) protocol: thisprotocol is used for assessment of filtration and tubular secretion,perfusion described by quantitative parameters (ml/min/gr), coronaryflow reserve and parametric quantitation, under stress or restconditions. A patient is injected with up to about 1 mCi of 111-In-DTPAand 0.2 mCi of Tc-MAG3, with the camera running, and imaging is begunimmediately. Imaging is taken for a time of up to 10 minutes, with anenergy window of between 3 and 15%. This protocol enables the study offluid flow, rate of tracer uptake (passive or active), traceraccumulation and redistribution, tracer metabolism, and secretion and/orwashout (active or passive) of tracer/metabolites.

39. Kidney—renal function (111-In-DTPA and Hippuran I-123) protocol:this protocol is used for assessment of filtration and tubularsecretion, under rest or stress conditions. The perfusion is describedby quantitative parameters (ml/min/gr) and parametric quantitation. Apatient subjected to a pharmacological stress, for example, for example,by the administration of adenosine or to a physical stress, for exampleby exercising on a treadmill. At the peak stress level, the patient isinjected with 0.3 mCi of 111-In-DTPA and up to 10 mCi of Hippuran I-123,with the camera running, and imaging is begun immediately. Imaging istaken for a time of up to 15 minutes, with an energy window of between 3and 15%. This protocol enables the study of fluid flow, rate of traceruptake (passive or active), tracer accumulation and redistribution,tracer metabolism, and secretion and/or washout (active or passive) oftracer/metabolites.

40. Brain perfusion protocol: this protocol is used for perfusionmapping under rest or stress conditions. The perfusion is described byquantitative parameters (ml/min/gr), cerebral flow reserve (in stressprotocols using pharmacological stress agents), parametric quantitation,and disease signature (Alzheimer's, depression, schizophrenia, etc.). Apatient is injected with up to about 20 mCi HMPAO, 99m labeled Tc-99mECD (neurolite), and up to 5 mCi I-123, with the camera running, andimaging is begun immediately. Imaging is taken for a time of up to 30minutes, with an energy window of between 3 and 15%. This protocolenables the study of fluid flow, rate of tracer uptake (passive oractive), tracer accumulation and redistribution, tracer metabolism, andsecretion and/or washout (active or passive) of tracer/metabolites.

41. Brain perfusion protocol: this protocol is used for perfusionmapping under rest or stress conditions. The perfusion is described byquantitative parameters (ml/min/gr), cerebral flow reserve (in stressprotocols using pharmacological stress agents), parametric quantitation,and disease signature (Alzheimer's, depression, schizophrenia, etc.). Apatient subjected to a pharmacological stress, for example, for example,by the administration of adenosine or to a physical stress, for exampleby exercising on a treadmill. At the peak stress level, the patient isinjected with up to about 20 mCi Tc-99m and up to about 5 mCiteboroxime, with the camera running, and imaging is begun immediately.Imaging is taken for a time of up to 30 minutes, with an energy windowof between 3 and 15%. This protocol enables the study of fluid flow,rate of tracer uptake (passive or active), tracer accumulation andredistribution, tracer metabolism, and secretion and/or washout (activeor passive) of tracer/metabolites.

42. Hepatobiliary Tc-99m sulfur colloid protocol: this protocol is usedfor looking at the liver structure (hemangiomas, abcesses, liverenlargement, etc.) under rest or stress conditions. A patient isinjected with up to about 5 mCi Tc-99m sulfur colloid, with the camerarunning, and imaging is begun immediately. Imaging is taken for a timeof up to 10 minutes, with an energy window of between 3 and 15%. Thisprotocol enables the study of fluid flow, rate of tracer uptake (passiveor active), tracer accumulation and redistribution, tracer metabolism,and secretion and/or washout (active or passive) of tracer/metabolites.

43. Liver function study protocol: this protocol is used for imagingunder rest or stress conditions. A patient subjected to apharmacological stress, for example, for example, by the administrationof adenosine or to a physical stress, for example by exercising on atreadmill. At the peak stress level, the patient is injected with up toabout 10 mCi Tc-99m disida (disulfenine), choletec, HIDA, (all bind tobilirubin sites)teboroxime, with the camera running, and imaging isbegun immediately. Imaging is taken every 5 minutes, for a time of 5minutes, for up to an hour, with an energy window of between 3 and 15%.If no activity is seen in the intestine, a pharmacological agent is usedfor gall bladder contraction. This protocol enables the study of fluidflow, rate of tracer uptake (passive or active), tracer accumulation andredistribution, tracer metabolism, and secretion and/or washout (activeor passive) of tracer/metabolites.

44. Dual phase gastric emptying study protocol: this protocol is usedfor determining the rate that the stomach empties of food. With thecamera running, imaging is begun immediately before the patient injectssolid food that is labeled with Tc99m-S-colloid or liquid food that islabeled with In-111-DTPA labeled. The study continues until the stomachis approximately empty of all tracer.

45. Cardiac vulnerable plaque study protocol: this protocol is used forfinding plaques that may be a nidus for initiating a CVA. A patient isinjected with up to 5 mCi of Annexin radiopharmaceutical containing111-In-DTPA imaging isotope and up to 5 mCi of AcuTecradiopharmaceutical containing Tc-99m-sestamibi and waits for 24 hoursand imaging begins. AcuTec attaches to activated platelets and showsthrombus. Annexin attaches to apoptotic cells; apoptotic cells beinghuman neutrophils that have died and broken up, demonstratinginflammatory infiltrate. This protocol enables the study of dynamicplaques that are associated with cardiac plaque tissue damage andrepair.

46. Prostate imaging study protocol: this protocol is used fordetermining the presence and/or extent of metastatic and/or primarycancer in the prostate. A patient is injected with up to 5 mCi ofProstascint radiopharmaceutical, containing 111-In-DTPA imaging isotopeand waits for 24-72 hours and imaging begins. This protocol enables thestudy of dynamic plaques that are associated with tissue damage andrepair.

47. SST-receptor imaging study protocol: this protocol is used fordetermining the presence and/or extent of SST-receptor expressingtumors, whether metastatic and/or primary cancerous tumors. A patient isinjected with up to 5 mCi of Octreotide radiopharmaceutical, containing111-In-DTPA imaging isotope and waits for 24-72 hours and imagingbegins. This protocol enables the study of SST-receptor expressingtumors metastatic and/or primary cancerous tumors.

48. Neuroendocrine tumors imaging study protocol: this protocol is usedfor determining the presence and/or extent of metastatic and/or primaryNeuroendocrine tumors by binding to associated Somatostatin receptors. Apatient is injected with up to 20 mCi of Neotec radiopharmaceutical,containing Tc-99m-sestamibi imaging isotope and waits for 24 hours andimaging begins. This protocol enables the study of Neuroendocrinetumors.

49. Thrombus detection imaging study protocol: this protocol is used forimaging DVT and intratererial thromus in coronary and carotid arteries,by binding to GP IIb/IIIa receptors on platelets. A patient is injectedwith up to 20 mCi of Acutect radiopharmaceutical, containingTc-99m-sestamibi imaging isotope and waits for 0-20 minutes and imagingbegins. This protocol enables the study of Thrombus detection, includingDVT and intratererial thromus in coronary and carotid arteries.

50. Pheochromocytoma and or Myocardial failure imaging study protocol:this protocol is used for imaging pancreatic adrenergic tissue uptakeand presynaptic adrenergic receptors, adrenergic being associated withadrenaline, by binding to GP IIb/IIIa receptors on platelets. A patientis injected with up to 5 mCi of MIBG Radiopharmaceutical, containingI-123 iofetamine hydrochloride imaging isotope and waits for 24 hoursand imaging begins. This protocol enables the study of tissue andreceptors that are associated with adrenergic uptake.

51. A gated cardiac stress imaging protocol: a dynamic study toinvestigate the effects of stress, for example adenosine, ice-water,and/or vasodilatation agents, on blood flow kinetics. A patient isinjected with about 4 mCi of Th-201-thallous chloride, some time priorto the imaging. After a waiting period of 0-2 minutes, a rest imaging ofabout 2-5 minutes is taken. The patient is then administered adenosine,ice-water, and/or vasodilatation agents. After a waiting period of about0-5 minutes an imaging of about 2-10 minutes is taken.

52. A Kidney function imaging protocol: a dynamic study to investigatethe effects of stress on blood flow kinetics (captopril; fusides etc) ofthe kidneys. A patient is injected with about 2-4 mCi Indium and/orTc-MAG3, while remaining substantially at rest. A rest imaging of about10-30 minutes is taken. After a waiting period of about 10-30 minutes,imaging of about 2 minutes is taken.

53. A Bexaar dosimetry imaging protocol: a study to determine the doserequired to inject in order to administer an effective dose of 75 REM. Apatient is injected with about 5 mCi/35 mg protein of, I-123 iofetaminehydrochloride, some time prior to each scan; each scan having an energywindow anywhere between 3-15% and lasting approximately five minutes.Three acquisitions are acquired during the week to produce a graph ofmetabolism.

Protocols for Multiple Radiopharmaceuticals

A combination of at least two radiopharmaceuticals may be used forspecific imaging protocols. Such a combination may be used, for example,to obtain information regarding both a pathology and an anatomy, suchthat the location of an imaged pathology within the body is identified;or to identify multiple pathologies in different sections of the body ofa subject; or to study different pathological processes within a singleorgan of a subject.

The individual radiopharmaceuticals may be administered sequentially orsubstantially simultaneously. Preferably, the radiopharmaceuticals areadministered as a single composition.

Combinations for the Study of a Pathology and an Anatomy:

1. Thallium-201-thallous chloride (a parathyroid avid agent) andTc-99m-pertechnetate (a thyroid agent) may be administered incombination for parathyroid adenoma imaging, and anatomicaldifferentiation of the parathyroid from the thyroid. A patient isinjected up to about 1 mCi Thallium-201-thallous chloride, and up toabout 15 mCi a dose of Te-99m. After a waiting time of about 10 minutes,imaging is taken for a period of about 5 minutes, with an energy windowof between 2 and 10 percent.

2. Tc-99m-methoxyisobutylisonitrile (sestamibi) (a parathyroid avidagent) and I-123 (a thyroid agent) may be administered in combinationfor parathyroid adenoma imaging, and anatomical differentiation of theparathyroid from the thyroid. A patient is injected with up to about 15mCi Tc-99m-sestamibi and up to about 100 μCi I-123. After a waiting timeof about 10 minutes, imaging is taken for a period of about 5 minutes,with an energy window of between 2 and 10 percent.

3. I-123 and Tc-99m-labeled red blood cells or Tc-99m-dihydrogenmethylenediphosphate (medronate MDP) may be administered in combinationfor imaging of thyroid cancer and identification of the location of thecancer. Tc99m-MDP is a bone-imaging agent, which enables visualizationof the skeleton to provide anatomical landmarks. Tc99m-labeling of redblood cells enables the larger blood vessels to be visualized to provideanatomical landmarks.

A patient is injected with up to about 4 mCi thallium-201-thallouschloride, and up to about 10 mCi of MDP. After a waiting time of up toabout 2 hours, imaging is taken for a period of up to about 30 minutes,with an energy window of between 2 and 10 percent.

4. In-111-L-Cysteinamide,D-phenylalanyl-L-cysteinyl-L-phenylalanyl-D-tryptophyl-L-lysyl-L-threonyl-N-[2-hydroxy-1-(hydroxy-methyl)propyl]-, cyclic 7)-disulfide (In-111-octreotide) and Tc-99m-MDP may beadministered in combination to optimally localize certain endocrinetumors. In-111-Octreotide is a tumor imaging agent forsomastatin-receptor expressing tumors. Tc99m-MDP is a bone-imagingagent, which enables visualization of the skeleton to provide anatomicallandmarks.

A patient is injected with up to about 4 mCi In-111-octreotide, and upto about 15 mCi of Tc-99m-MDP. Within 3 days of injection ofIn-111-octreotide, but not more than 2 hours after injection ofTc-99m-MDP, imaging is taken for a period of up to about 30 minutes,with an energy window of between 2 and 10 percent. Hence, for example,the two radiopharmaceuticals may be administered substantiallysimultaneously, and imaging taken within 2 hours of injection.Alternatively, In-111-octreotide may be injected first, and imagingtaken within 3 days of this injection, with Tc-99m-MDP injected at alater time point, no more than 2 hours prior to imaging.

5. In-111-capromab pendetide and Tc-99m-labeled red blood cells (RBCs)may be administered for delineating vascular structures of the pelvis orabdomen, and enabling the clinician to distinguish the blood vesselsfrom the lymph nodes by pathologic uptake of antibodies. In-111-capromabpendetide is a monoclonal anti-tumor antibody to prostate specificmembrane antigen (PMSA).

A patient is injected with up to about 3 mCi In-111-capromab pendetide,and up to about 15 mCi of Tc-99m-RBCs. Within 3 days of injection ofIn-111-capromab pendetide, but not more than 2 hours after injection ofTc-99m-RBCs, imaging is taken for a period of up to about 30 minutes,with an energy window of between 2 and 10 percent.

6. Tc-99m-colloid and In-111-white blood cells (WBCs) may beadministered in combination for the identification and localization ofbone infection. A patient is injected with up to about 15 mCiTc-99m-colloid, and up to about 3 mCi of In-111-WBCs. Within 3 days ofinjection of In-111-WBC, but not more than 2 hours after injection of TcTc-99m-colloid, imaging is taken for a period of up to about 30 minutes,with an energy window of between 2 and 10 percent.

7. Tl-201-thallous chloride (a tumor imaging agent) and Tc-99m-MDP (abone scan agent) may be administered in combination to evaluate theinvasion of bone or cartilage by head or neck cancer. A patient isinjected with up to about 2 mCi thallium-201-thallous chloride, and upto about 15 mCi of MDP. After a waiting time of up to about 2 hours,imaging is taken for a period of up to about 30 minutes, with an energywindow of between 2 and 10 percent.

Combinations for the Study of Multiple Pathologies:

8. Tl-201-thallous chloride, Te-99-m-sestamibi, and In-111-white bloodcells may be administered in combination for the assessment of variouspathological conditions, including cardiac conditions, tumors, andinfection. A patient is injected with up to about up to about 1 mCiTl-201-thallous chloride, up to about 10 mCi of Te-99-m-sestamibi, andup to about 2 mCi In-111-WBCs. After a waiting time of up to about 24hours, imaging is taken for a period of up to about 30 minutes, with anenergy window of between 2 and 10 percent.

9. Tl-201-thallous chloride, Te-99-m-MDP, and In-111-white blood cellsmay be administered in combination for the assessment of variouspathological conditions, including cardiac conditions, tumors, andinfection. A patient is injected with up to about 1 mCi Tl-201-thallouschloride, up to about 10 mCi of Te-99-m-MDP, and up to about 2 mCiIn-111-WBCs. After a waiting time of up to about 24 hours, imaging istaken for a period of up to about 30 minutes, with an energy window ofbetween 2 and 10 percent.

Combinations for the Study of Different Pathological Processes of theSame Organ:

10. Tl-201-thallous chloride, Tc-99m-teboroxime or Tc-99m-sestamibi, andI-123-beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) may beadministered in combination for the study of acute myocardial ischemia.A patient is injected with up to about 1 mCi Tl-201-thallous chloride,up to about 10 mCi Tc-99m-teboroxime or Tc-99m-sestamibi, and up toabout 2 mCi I-123-beta-methyl-p-iodophenylpentadecanoic acid (BMIPP).After a waiting time of up to about 48 hours, imaging is taken for aperiod of up to about 30 minutes, with an energy window of between 2 and10 percent.

11. Tc-99m-Fanoselomab and In-111-white blood cells may be administeredin combination to study fever of unknown origin. A patient is injectedwith up to about 15 mCi 99m-Fanoselomab and up to about 2 mCiIn-111-white blood cells. After a waiting time of up to about 24 hours,imaging is taken for a period of up to about 30 minutes, with an energywindow of between 2 and 10 percent.

12. I-123-iodobenzamide (IBZM) and Tc-99m-Exametazine (HMPAO) may beadministered in combination to study schizophrenia or Parkinson'sdisease. A patient is injected with up to 2 mCi I-123-iodobenzamide(IBZM) and up to about 15 mCi Tc-99m-Exametazine (HMPAO). After awaiting time of up to about 48 hours, imaging is taken for a period ofup to about 30 minutes, with an energy window of between 2 and 10percent.

13. In-111-labeled antibody, Tc-99m-sestamibi or Tc-99m-Arcitumomab andTl-201-thallous chloride may be administered in combination for tumoridentification and characterization by perfusion studies. A patient isinjected with up to about 1 mCi I-111-labeled antibody, up to about 10mCi Tc-99m-sestamibi or Tc-99m-Arcitumomab, and up to about 1 mCiTl-201-thallous chloride. After a waiting time of up to about 24 hours,imaging is taken for a period of up to about 30 minutes, with an energywindow of between 2 and 10 percent.

14. In-111-diethylene triamine pentaacetate (DTPA) andTc-99m-mercaptoacetyltriglycine (MAG3) may be administered incombination for dynamic flow studies for the investigation of renalfunction. A patient is injected with up to about 2 mCi In-111-diethylenetriamine pentaacetate (DTPA) and up to about 15 mCiTc-99m-mercaptoacetyltriglycine (MAG3). After a waiting time of up toabout 24 hours, imaging is taken for a period of up to about 30 minutes,with an energy window of between 2 and 10 percent.

15. Tl-201-thallous chloride and Tc-99m-teboroxime or Tc-99m-sestamibimay be administered in combination for the study of tumor perfusion andtherapeutic response. A patient is injected with up to about 1 mCiTl-201-thallous chloride and up to about 15 mCi Tc-99m-teboroxime orTc-99m-sestamibi. After a waiting time of up to about 1 hour, imaging istaken for a period of up to about 30 minutes, with an energy window ofbetween 2 and 10 percent.

16. Tc-99m-sulfur colloid and In-111-WBCs may be administered incombination to differentiate between infection and bone marrowactivation. A patient is injected with up to about 15 mCi Tc-99m-sulfurcolloid and up to about 2 mCi In-111-WBCs. After a waiting time of up toabout 24 hours, imaging is taken for a period of up to about 30 minutes,with an energy window of between 2 and 10 percent.

17. Tc-99m-MDP and In-111-WBCs may be administered in combination todifferentiate between acute and chronic acute osteomyelitis. A patientis injected with up to about 15 mCi Tc-99m-MDP and up to about 2 mCiIn-111-WBCs. After a waiting time of up to about 24 hours, imaging istaken for a period of up to about 30 minutes, with an energy window ofbetween 2 and 10 percent.

18. Gallium-67 and In-111-WBCs may be administered in combination todifferentiate between acute and chronic inflammation. A patient isinjected with up to about 5 mCi gallium-67 and up to about 2 mCiIn-111-WBCs. After a waiting time of up to about 72 hours, imaging istaken for a period of up to about 30 minutes, with an energy window ofbetween 2 and 10 percent.

19. Tc-99m-teboroxime or Tl-201-thallous chloride and In-111-annexin maybe administered in combination to study myocardial perfusion andapoptosis. A patient is injected with up to about 15 mCiTc-99m-teboroxime or up to about 2 mCi Tl-201-thallous chloride and upto about 2 mCi In-111-annexin. After a waiting time of up to about 24hours, imaging is taken for a period of up to about 30 minutes, with anenergy window of between 2 and 10 percent.

20. Tl-201-thallous chloride and Tc-99m-pyrophosphate may beadministered in combination to investigate myocardial perfusion andinfarct. A patient is injected with up to about 2 mCi Tl-201-thallouschloride and up to about 15 mCi Tc-99m-pyrophosphate. After a waitingtime of up to about 1 hour, imaging is taken for a period of up to about30 minutes, with an energy window of between 2 and 10 percent.

Protocols for Non-Coincidence Imaging Using PET Radiopharmaceuticals

The following imaging protocols use non-coincidence imaging using PETradiopharmaceuticals, as is further described in the Tables shown inFIGS. 148 A-V:

1. Use of F-18-Fluorodeoxyglucose (FDG), as a substrate for hexokinasein glucose metabolism, for the study of glucose metabolism of cellsincluding tumor, heart and brain cells.

2. Use of F-18-Fluoromisonidazole for imaging of hypoxia and oxidativemetabolism, with the clinical application of radiotherapy treatmentplanning.

3. Use of F-18-3′-Fluoro-3′-deoxythymidine (FLT) for the study of DNAsynthesis.

4. Use of F-18-Fluoromethyl choline (FCH) as a choline precursor forcell membrane synthesis, for the study of choline metabolism of tumors.

5. Use of F-18-4-Fluoro-m-tyrosine (FMT) as a precursor for dopaminesynthesis and as a substrate for aromatic amino acid decarboxylase(AAAD), with the clinical application of imaging brain tumors.

6. Use of F-18-6-Fluoro-L-DOPA as a precursor for dopamine synthesis andas a precursor for AAAD, with the clinical applications of imaging andgrading Parkinson's disease and imaging neuroendocrine tumors.

7. Use of F-18-FP-β-CIT for binding to the dopamine transporter indopaminergic axons, with the clinical application of imaging and gradingParkinson's disease and imaging neuroendocrine tumors.

8. Use of F-18-Pencyclovir (FHBG) to target thymidine kinase, with theclinical application of imaging reporter gene expression.

9. Use of F-18-Fluoroestradiol (FES) to target estrogen receptors, withthe clinical application of breast tumor imaging.

10. Use of C-11-Methionine to target amino acid synthesis, with theclinical application of imaging brain tumors.

11. Use of In-111-Pentetreotide (Octreoscan®) to target somatostatinreceptors, with the clinical application of imaging neuroendocrinetumors.

12. Use of Tc-99m-P829, (Neotec®) to target somatostatin receptors, withthe clinical application of imaging neuroendocrine tumors.

13. Use of Tc-99m-P280, Acutect® to target GP IIb/IIIa receptors onplatelets, with the clinical applications of detection of thrombosis,such as deep vein thrombosis (DVT) and intratererial thrombosis incoronary and carotid arteries.

14. Use of I-123-vasoactive intestinal peptide (VIP) to target VIPreceptors, with the clinical application of imaging gastrointestinaltumors.

15. Use of I-123-MIBG (meta-iodo benzyl guanidine) to target adrenergictissue uptake and presynaptic adrenergic receptors, with the clinicalapplication of tumor imaging (Pheochromocytoma) and myocardial failureimaging.

16. Use of I-123-NP-59 to target the low-density lipoprotein (LDL)receptor and cholesterol metabolism, with the clinical application ofimaging of adrenal carcinoma, adenoma, and Cushing's syndrome.

17. Use of C-11-Raclopride to target dopamine D2 receptors, for brainimaging of dopamine D2 receptors in schizophrenia, and assessment ofdose for neuroleptics.

18. Use of I-123-iodobenzamide (IBZM) to target dopamine D2 receptors,for brain imaging of dopamine D2 receptors in schizophrenia, andassessment of dose for neuroleptics.

19. C-11-carfentanil to target Mu opioid receptors in brain, with theclinical application of imaging drug addiction.

20. Use of C-11-α-methyl-L-tryptophan as a precursor for α-methylserotonin synthesis and as a substrate for AAAD enzyme, with theclinical application of imaging depression.

21. Use of C-115-Hydroxytryptophan as a precursor for serotoninsynthesis with the clinical application of imaging neuroendocrinetumors.

22. Use of F-18-MPPF to bind to 5-HT1A (5-hydroxytryptamine-1A)serotonin receptors, with the clinical application of imaging depressionand epilepsy.

23. Use of F-18-Altanserin to bind to 5-HT2A serotonin receptors withthe clinical application of imaging depression and epilepsy.

24. Use of C-11-Acetate for the study of tricarboxylic acid cycleactivity and oxidative metabolism with the clinical application ofstudying myocardial oxygen metabolism.

25. Use of C-11-Palmitate as a precursor for fatty acid metabolism withthe clinical application of imaging myocardial metabolism.

26. F-18-Fluorodopamine to target presynaptic adrenergic receptors

Protocols for Beta Emitting Radiopharmaceuticals

The following beta emitting radionuclides may be used for diagnosticstudies, using a dose of about 1 mCi, using the camera of the presentinvention: Sm-153 (T_(1/2) 1.95 days), I-131 (T_(1/2) 8.04 days), Cu-67(T_(1/2) 2.58 days), Lu-177 (T_(1/2) 6.7 days), and Sn-117m (T_(1/2)13.6 days). These include both long-lived radiopharmaceuticals andradiopharmaceuticals with low abundance gamma.

Protocols for Long-Lived Radiopharmaceuticals

Long-lived radiopharmaceuticals suitable for use with the camera of thepresent invention include I-131 and Sn-117m.

Protocols for Radiopharmaceuticals with Low Abundance Gamma

Cu-67, Lu-177 and Sm-153

Section I: Technetium-Labeled Radiopharmaceuticals

Technetium exists only in the form of radioactive isotopes. Tc-99 has ahalf life of 21000 years. The widely used Tc-99m is an isomer of Tc-99,which decays to Tc-99, and has a half life of 6.02 hours, emitting agamma ray of 141 KeV.

The short half-life makes storing impractical, even for a weekly supply.Therefore, a Tc-99m radionuclide generator is employed, on site, usingthe parent, Mo-99, which has a half-life of 67 hours. In theradionuclide generator, the parent is retained in such a way that thedaughter can be easily separated for clinical use.

A decay curve of Mo-99 to Tc-99m and to Tc-99 is seen in FIG. 144, whilea build-up and decay graph for both Tc-99m and Tc-99 is seen in FIG.145. The buildup of Tc-99 occurs both by decay of the isomeric Tc-99m toTc-99 and by the direct decay of Mo-99 to Tc-99, so the total Tc-99,from a chemical standpoint is the sum of Tc-99m and Tc-99, at any pointin time.

In general, a Mo-99 to Tc-99m generator uses an alumina (Al₂O₃) column,such as (NH₄)2 ⁹⁹MoO₄ (ammonium molybdate). The Mo-99 decays to Tc-99mand Tc-99, which exist in a TcO₄ ⁻ form (pertechnetate), weakly bound tothe alumina column.

Elution takes place by an isotonic saline, replacing the weakly boundTcO₄ ⁻ with Cl⁻. The chemical form of Tc in the eluant is NaTcO₄, knownas sodium pertechnetate, which includes both Tc-99m-sodium pertechnetateand Tc-99-sodium pertechnetate.

A normal elution cycle is 24 hours, as described in FIG. 145.

A recommended low-dose elution cycle will take place every 23 hours,then again an hour later, to provide low dose Tc-99m, as seen in FIG.146.

A. Tc-99m-Teboroxime for Myocardial Perfusion Imaging, at Rest

Tc-99m-teboroxime is a natural boronic acid adduct of technetium dioximecomplexes, which is highly lipophilic. Therefore it crosses cellmembranes easily, with no involvement of active metabolic processes.Excretion is primarily enterohepatic, with peak hepatic uptake at about6 minutes following injection.

In myocardial perfusion imaging protocols, separate rest and stressinjections are given. Tc-99m-teboroxime has a high myocardial extractionfraction, of about 90%, and rapid myocardial washout, greater than about70%. The myocardial biological half-life is between 10 and 11 minutes,and most of the administered Tc-99m-Teboroxime is undetectable afterabout 20 to 22 minutes.

Tebroxime Labeling Kit and Technique:

U.S. Pat. No. 6,056,941, to Schramm, et al., issued on May 2, 2000,describes a tebroxime labeling kit, by Cardiotec®, Bracco Diagnostics.The kit is provided as a reaction vial, containing a sterile,nonpyrogenic, lyophilized formulation of:

-   -   2 mg cyclohexanedione dioxime;    -   2 mg methyl boronic acid;    -   2 mg pentetic acid;    -   9 mg citric acid;    -   100 mg sodium chloride;    -   50 mg 2-hydroxypropyl gamma cyclodextrin; and    -   0.02-0.058 mg tin as stannous chloride SnCl₂.

For labeling, 1 ml sodium pertechnetate, containing Tc-99m, is added tothe vial at a desired dose of between 10 and 100 mCi, in physiologicalsaline, to provide Tc-99-teboroxime.

Standard-Dose Example

For cardiac perfusion, a standard-dose of imaging at stress may be 30mCi. For practical reasons, the injection solution is preferably between1 ml and 3 ml. In other words, the solution should be prepared so as toavoid situations, where an injection of 0.1 ml or of 80 ml is requiredin order to meet the required dose, since this would be technicallyimpractical.

Standard-Dose Preparation:

Assume the sodium pertechnetate, has been assayed and found to have aTc-99m radioactivity of 90 mCi per ml.

Example 1 standard-dose preparation proceeds as follows:

Combine:

1 ml of the sodium pertechnetate, having a total Tc-99m radioactivity of90 mCi; and

the contents of a reaction vial, containing a sterile, nonpyrogenic,lyophilized formulation as described above,

to form:

about 1 ml injection solution, having the total Tc-99m radiation dose of90 mCi, dilute:

the injection solution by a ratio of 1:3 by addition of 2 ml salinesolution to give a total volume of 3 ml; and

inject:

1 ml of the diluted solution, for a total Tc-99m radiation dose of 30mCi.

Low-Dose Example

For cardiac perfusion, a low dose of imaging at stress may be 3 mCi,about a tenth of the standard-dose. Again, for practical reasons, theinjection solution is preferably between 1 ml and 3 ml.

Low-Dose Preparation Example 1

In this example, a low dose of 3 mCi, is achieved by a standard-and-lowdose elution process, where elution takes place every 23 hours for thestandard dose, and an hour later, for the low dose.

Assume the sodium pertechnetate from a low-dose elution, has beenassayed and found to have a Tc-99m radioactivity of 10 mCi per ml. Thesolution may be diluted to provide an injection solution having aradioactivity dose of about 3 mCi per ml by dilution by a factor ofabout 1:3 using standard methods. 1 mCi diluted solution is added to thelyophilized formulation described above, and the full 1 ml injected toprovide a total dose of about 3 mCi.

It will be appreciated that two generators, one for low dose and one forstandard dose may be employed.

Low Dose Preparation Example 2

A low dose injection solution may be prepared by diluting a standardsolution of Tc-99m-sodium pertechnetate by known methods.

Assume the sodium pertechnetate, has been assayed and found to have aTc-99m radioactivity of 90 mCi per ml. This solution may be diluted by afactor of about 1:30, for example by withdrawing 1 ml of the standardsolution and adding 29 ml saline solution to produce a diluted injectionsolution containing about 3 mCi per ml. 1 ml of the diluted injectionsolution is then withdrawn and added to the to the lyophilizedformulation described above, and the full 1 ml injected to provide atotal dose of about 3 mCi.

Low-Dose Preparation Example 3

A low dose injection may be prepared by withdrawing a volume providingthe required dose of radioactivity from a standard preparation ofTc-99m-sodium pertechnetate, using specialized measuring instruments ofhigh accuracy. Such instruments are known in the art, and may be usedfor measuring of a volume of up to 0.5 ml. The instruments are graduatedat intervals of 0.05 ml, and are provided with a radiation shield.

Assume the sodium pertechnetate, has been assayed and found to have aTc-99m radioactivity of 90 mCi per ml. A radiation dose of about 9 mCiwill be provided by 0.1 ml. A volume of 0.1 ml is withdrawn, thesolution is then diluted by addition of 0.2 ml saline solution toprovide a solution having a total radiation dose of 3 mCi in 0.3 ml.This solution may then be brought to a final volume of at least 1 ml forinjection.

B. Sestamibi For Breast Tumor Imaging

Sestamibi (methoxyisobutylisonitrile) is a lipophilic monovalent cation,which enters the cell via passive diffusion across plasma andmitochondrial membranes. Blood clearing occurs with a half life of 4.3minutes at rest, and 1.6 minutes under exercise conditions. At 5 minutespost injection, about 8% of the injected dose remains in circulation.There is less than 1% Tc-99m-sestamibi protein binding in plasma. Themyocardial biological half-life is approximately 6 hours after a rest orexercise injection. The major pathway for clearance of Tc-99m-sestamibiis the hepatobiliary system.

Sestamibi Labeling Kit and Technique:

A kit for the preparation of Tc-99m-sestamibi for is supplied by BristolMyers Squibb, containing a sterile non-pyrogenic, lyophilized mixtureof:

-   -   1 mg of 2-methoxy isobutyl isonitrile copper (I)        tetrafluoroborate    -   2.6 mg of sodium citrate dihydrate    -   1 mg of L-cysteine hydrochloride monohydrate    -   20 mg mannitol    -   0.025-0.075 stannous chloride dihydrate    -   up to 0.086 mg tin chloride

Sodium pertechnetate, containing Tc-99m, at a dose of between 25-150mCi, in physiological saline at a volume of 1-3 ml is added, to provideTc-99-sestamibi.

Standard-Dose Example

For breast tumor imaging, a standard dose used is 20-30 mC, in a volumeof between 1 ml and 3 ml.

Standard-Dose Preparation

A standard dose may be prepared by addition of a standard preparation ofTc-99m-sodium pertechnetate to a vial containing the lyophilizedformulation as described above, and diluted as necessary, by methodsknown in the art, as described above for Tc-99m-Teboroxime.

Low-Dose Example

For breast tumor imaging, a low dose of imaging at stress may be 2-3mCi, about a tenth of the standard-dose. Again, for practical reasons,the injection solution is preferably between 1 ml and 3 ml.

Low-Dose Preparation:

A low dose may be prepared as for any of the examples described abovefor Tc-99m-Teboroxime.

C. Tc-99m-Tetrofosmin for Myocardial Perfusion Imaging

Tetrofosmin is[6,9-bis(2-ethoxyethyl)-3,12-dioxa-6,9-diphosphatetradecane], which islabeled with Tc-99m to form a lipophilic, cationic complex, used formyocardial perfusion imaging. The heart uptake of Tc-99m-tetrofosmin israpid and retention good, with approximately 1% of the injected doseremaining at 120 minutes post-injection. Clearance from lungs and liveris rapid, with activity practically undetectable within 4 or 8 hours,respectively, of injection. Blood and plasma clearance are also rapid,such that less than 5% of the injected dose remains in blood by 10minutes post-injection, and less than 3.5% remain in plasma.

Tetrofosmin Labeling Kit and Technique:

A kit for the preparation of Te-99m-tetrofosmin for injection isproduced by Amersham Health. The kit comprises a sterile, non-pyrogenic,lyophilized mixture of:

-   -   0.23 mg tetrofosmin;    -   0.03 mg stannous chloride dihydrate;    -   0.32 disodium sulphosalicyclate;    -   1 mg sodium D-gluconate; and    -   1.8 mg sodium hydrogen carbonate.

To this mixture is added 4-8 ml Tc-99m-sodium pertechnetate containing30mCi/ml in physiological saline, to provide Tc-99m-tetrofosmin of up to240 mCi.

Standard-Dose Example

For cardiac imaging, a standard dose used is 20-30 mC, in a volume ofbetween 1 ml and 3 ml.

Standard-Dose Preparation Example

A standard dose may be prepared by addition of a standard preparation ofTc-99m-sodium pertechnetate to a vial containing the lyophilizedformulation as described above, and diluted as necessary, by methodsknown in the art, as described above for Tc-99m-Teboroxime.

Low-Dose Example

For cardiac imaging, a low dose of imaging is 2-3 mCi, about a tenth ofthe standard-dose. Again, for practical reasons, the injection solutionis preferably between 1 ml and 3 ml.

Low-Dose Preparation Example

A low dose may be prepared as for any of the examples described abovefor Tc-99m-Teboroxime.

D. Tc-99m-medronate (MDP) for Bone Imaging

Tc-99m-medronate (disodium dihygrogen methylenediphosphate) is used as askeletal imaging agent to delineate areas of abnormal osteogenesis, suchas those that occur with metastatic bone disease, Paget's disease,arthritic disease, osteomyelitis and fractures. It is generally acceptedthat technetium Tc-9m-medronate localizes on the surface ofhydroxyapatite crystals by a process termed chemisorption, with bloodflow and/or blood concentration being most important in the delivery ofthe agent to sites of uptake. Visualization of osseous lesions ispossible since skeletal uptake of technetium Tc-99m-medronate is alteredin areas of abnormal osteogenesis.

During the initial 24 hours following intravenous injection ofTc-99m-medronate, about 50 percent of the dose is retained in theskeleton, and about 50% is excreted in the urine. Clearance ofradioactivity from the blood is quite rapid, with about 10% of theinjected dose remaining at 1 hour, and less than 5 and 2% at 2 and 4hours, respectively.

Tc-99m-MDP Labeling Kit and Technique:

Kits for the preparation of Tc-99m-MDP are produced by BraccoDiagnostics; Draximage; Amersham Healthcare; and Mallicknrodt.

Standard-Dose Example

For bone imaging, a standard dose of 20 mCi is used.

Standard-Dose Preparation:

The kit provided by Draximage comprises a vial containing a sterile,non-pyrogenic, non-radioactive lyophilized mixture of:

-   -   10 mg medronic acid;    -   0.8-1.21 mg stannous chloride dihydrate; and    -   2 mg p-aminobenzoic acid.

The pH is adjusted with sodium hydroxide or hydrochloric acid to 6.5-7.5prior to lyophilization. The pH of the reconstituted product is 5.4 to6.8.

For reconstitution, 2-10 ml of Tc-99m-sodium pertechnetate is added,providing up to 500 mCi.

A standard dose may be prepared by addition of a standard preparation ofTc-99m-sodium pertechnetate to a vial containing the lyophilizedformulation as described above, and diluted as necessary, by methodsknown in the art, as described above for Tc-99m-Teboroxime.

Standard-Dose Preparation:

A standard dose may be prepared by addition of a standard preparation ofTc-99m-sodium pertechnetate to a vial containing the lyophilizedformulation as described above, and diluted as necessary, by methodsknown in the art, as described above for Tc-99m-Teboroxime.

Low-Dose Example

For bone imaging, a low dose may be 2 mCi, about a tenth of thestandard-dose. Again, for practical reasons, the injection solution ispreferably between 1 ml and 3 ml.

Low-Dose Preparation:

A low dose may be prepared as for any of the examples described abovefor Tc-99m-Teboroxime.

E. Tc-99m-Mertiatide (MAG3) for Renal Imaging

Technetium-99m-mertiatide((N—[N—[N-(Mercaptoacetyl)glycyl]glycyl]-glycine benzoate) is indicatedas a renal imaging agent to assess renal perfusion, size, position,configuration, function (including differential renal function), upperurinary tract obstruction, and active urinoma. The use of this agent forrenal imaging is based on its clearance through the urinary tractpredominantly via active tubular secretion (almost exclusively by theproximal renal tubules) and to a small extent by glomerular filtration.The rate of appearance and excretion and the concentration of technetiumTc 99m mertiatide in the kidney can be monitored to assess renalfunction.

Technetium-99m-mertiatide is rapidly distributed in and cleared from theplasma. Systemic protein binding is between 70-90%, but is reversible.The agent is rapidly excreted by the kidneys via active tubularsecretion and glomerular filtration.

Tc-99m-Mertiatide Labeling Kit and Technique:

A kit for the preparation of Tc-99m-mertiatide is produced byMallicknrodt. The kit comprises a vial containing a sterile,non-pyrogenic, lyophilized powder, comprising

-   -   1 mg betiatide (N—[N—[N—[(benxoylthio)        acetyl]glycyl]glycyl]glycine)    -   0.2 mg stannous chloride dihydrate;    -   40 mg sodium tartrate dihydrate; and    -   20 mg lactose monohydrate.

For labeling, 4-10 ml of Tc-99m-sodium pertechnetate solution containing20-100 mCi is added.

Standard-Dose Example

For renal imaging, a standard dose of 10 mCi is used.

Standard-Dose Preparation:

A standard dose may be prepared by addition of a standard preparation ofTc-99m-sodium pertechnetate to a vial containing the lyophilizedformulation as described above, and diluted as necessary, by methodsknown in the art, as described above for Tc-99m-Teboroxime.

Low-Dose Example

For renal imaging, a low dose may be 1 mCi, about a tenth of thestandard-dose. Again, for practical reasons, the injection solution ispreferably between 1 ml and 3 ml.

Low-Dose Preparation:

A low dose may be prepared as for any of the examples described abovefor Tc-99m-Teboroxime.

F. Tc-99m-Exametazine (HMPAO) for Cerebral Imaging

Examatazine (hexamethylpropylene amine oxime, HMPAO) is[(R,R,S,S)-4,8-diaza-3,6,6,9-tetramethylundecamce-2,10-dione bisoxime].Tc-99m-HMPAO is commonly used for detection of altered regional cerebralperfusion and for the radiolabeling of autologous leukocytes.

Tc-99m-HMPAO is rapidly cleared from the blood after intravenousinjection. Uptake in the brain reaches a maximum of 3.5-7% of theinjected dose within 1 minute of injection. Up to 15% of the activity iseliminated from the brain by 2 minutes post injection, after whichlittle activity is lost for the following 24 hours, except by physicaldecay of Tc-99m. The activity not associated with the brain is widelydistributed throughout the body. About 30% of the injected dose is foundin the gastrointestinal tract immediately after injection, and about 50%of this is excreted through the intestinal tract over a 48 hour period.About 40% of the injected dose is excreted through the kidneys and urinewithin 48 hours post injection.

Tc-99m-HMPAO Labeling Kit and Technique:

A kit for the preparation of Tc-99m-HMPAO is produced by NycomedAmersham. The kit comprises:

a vial containing a sterile, non-pyrogenic, lyophilized powder,comprising

-   -   0.5 mg HPAO;    -   7.6 μg stannous chloride dihydrate; and    -   4.5 mg sodium chloride;

a vial containing 10 mg methylene blue in water; and

a vial containing sodium phosphate solution, each ml comprising:

-   -   0.276 mg monobasic sodium phosphate monohydrate;    -   0.142 mg dibasic sodium phosphate anhydrous; and    -   9 mg sodium chloride in water.

Standard-Dose Example

For cerebral imaging, a standard dose of 20 mCi is used.

Standard-Dose Preparation:

For preparation of Tc-99m-HMPAO, 0.5 ml methylene blue is added to thevial containing monobasic sodium phosphate and dibasic sodium phosphate.2 ml of this mixture is withdrawn. HMPAO is reconstituted with 5 mlTc-99m to provide a dose of 10-54 mCi, and the 2 ml methyleneblue/sodium phosphate mixture added.

The injection solution may be diluted as necessary, by methods known inthe art, as described above for Tc-99m-Teboroxime.

Low-Dose Example

For cardiac imaging, a low dose may be 2 mCi, about a tenth of thestandard-dose. Again, for practical reasons, the injection solution ispreferably between 1 ml and 3 ml.

Low-Dose Preparation:

A low dose may be prepared as for any of the examples described abovefor Tc-99m-Teboroxime.

G. Tc-99m-Mebrofenin for Hepatobiliary Imaging

Mebrofenin(2,2′-[[2-[(3-bromo-2,4,6-trimethylphenyl)-amino]-2-oxoethyl]imino]bisaceticacid) is an iminodiacetic acid derivative, which binds to plasmaproteins (mainly albumin). In the liver, in the space of Disse,Tc-99m-mebrofenin dissociates from the proteins and enters thehepatocyte by a mechanism similar to that of serum bilirubin.Tc-99m-mebrofenin traverses through the hepatocyte unmetabolized andenters the bile canaliculi. Flow beyond the canaliculi is influenced toa large extent by the tone of the sphincter of Oddi and the patency ofthe bile ducts. Clear visualization of the gall-bladder and intestines,usually within 15 to 30 minutes of administration, demonstrateshepatobiliary tract patency.

Tc-99m-HMPAO Labeling Kit and Technique:

A kit for the preparation of Tc-99m-Mebrofenin is manufactured by BraccoDiagnostics (Choletec™). The kit comprises a sterile, non-pyrogenicmixture comprising:

-   -   45 mg mebrofenin;    -   0.54-1.03 mg stannous fluoride dihydrate;    -   up to 5.2 mg methyl-paraben; and    -   0.58 propylparaben.

Standard Dose Example

For hepatobiliary imaging, a standard dose of 10 mCi is used.

Low-Dose Example

For cardiac imaging, a low dose may be 1 mCi, about a tenth of thestandard-dose. Again, for practical reasons, the injection solution ispreferably between 1 ml and 3 ml.

H. Tc-99m-Fanoselomab For Infectious Imaging

Fanoselomab is a monoclonal antibody for imaging of infection.Fanolesomab is directed against the carbohydrate moiety3-fucosyl-N-acetyllactosamine that defines the cluster ofdifferentiation 15 (CD15) antigen. Tc-99m-fanolesomab radiolabels humanwhite blood cells and myeloid precursors. The CD15 antigen is expressedon the surface of polymorphonuclear neutrophils, eosinophils andmonocytes.

Tc-99m-fanoselomab is indicated for imaging of patients with equivocalsigns and symptoms of appendicitis.

Tc-99m-Fanoselomab Labeling Kit and Technique:

A kit for the preparation of Tc-99m-Fanoselomab is manufactured byMallingkrodt (NeutroSpec™). The kit comprises a sterile, non-pyrogenicmixture comprising:

-   -   0.25 mg lanolesomab;    -   12.5 mg maltose monohydrate;    -   0.522 mg sodium potassium tartrate tetrahydrate;    -   0.221 mg succinic acid;    -   54 μg stannous tartrate;    -   28 μg glycine; and    -   9.3 μg disodium edetate dihydrate.

0.2-0.35 ml Tc-99m-sodium pertechnetate is added to the lyophilizedmixture, and ascorbic acid (500 mg/ml) added to make the finalpreparation volume up to 1 ml.

Standard Dose Example

For imaging of infection, a standard dose of 10-20 mCi is used.

Low-Dose Example

For imaging of infection, a low dose may be 1-2 mCi, about a tenth ofthe standard-dose. Again, for practical reasons, the injection solutionis preferably between 1 ml and 3 ml.

Section II:

I. Thallium-201 for Tumor Imaging

Thallium is a metal in group IIIA of the periodic table, with biologicalproperties similar to those of potassium. The distribution of thethallous ion following intravenous administration is primarilyintracellular. Transport of thallium across the cell membrane has beenreported to occur partly via an ouabain inhibitable mechanism, presumedto be the sodium-potassium ATPase pump.

Thallium-201, administered in the form of thallous chloride, is used formyocardial perfusion imaging and for parathyroid and tumor imaging. Thenormal net myocardial clearance half-life of Tl-201 after intravenousinjection is approximately 4 hours when the patient is injected duringexercise, and longer when the patient is injected at submaximal exerciseheart rate or at rest.

Thallium-201 has a half-life of 73 hours, and emits gamma-4 rays of 135KeV; gamma-6 rays of 167 KeV and mercury x-rays of 68-80 KeV.

Thallium Labeling Kit and Technique:

Thallium 201 is supplied by Amersham Healthcare, in an isotonic solutionas a sterile, non-pyrogenic diagnostic radiopharmaceutical forintravenous administration, comprising 1 mCi per ml, made isotonic with9 mg sodium chloride and preserved with 0.9% (v/v) benzyl alcohol. ThepH is adjusted to between 4.5 and 7.0 with hydrochloric acid and/orsodium hydroxide. Thallium TI 201 is cyclotron produced.

Standard-Dose Example

For tumor imaging, a standard dose of up to 3 mCi is used.

Standard-Dose Preparation:

3 ml of the injection solution are injected.

Low-Dose Example

For tumor imaging, a low dose of 0.3 mCi, about a tenth of thestandard-dose may be used. Again, for practical reasons, the injectionsolution is preferably between 1 ml and 3 ml.

Low-Dose Preparation:

A low dose may be prepared as for any of the examples described abovefor Tc-99m-Teboroxime.

Section III: Indium In-111-Labeled Radiopharmaceuticals

Indium In-111 has a physical half-life of about 6.2 hours (2.8 days),emitting gamma-2 rays with an energy of 171.3 KeV and gamma-3 rays withan energy of 245.4 KeV.

J: Octreotride for Neuroendocrine Tumor Imaging

Octreotide is the acetate salt of a cyclic octapeptide. It is along-acting octapeptide with pharmacologic properties mimicking those ofthe natural hormone somatostatin. Octreotide is known chemically asL-Cysteinamide,D-phenylalanyl-L-cysteinyl-L-phenylalanyl-D-tryptophyl-L-lysyl-L-threonyl-N-[2-hydroxy-1-(hydroxy-methyl)propyl]-,cyclic 7)-disulfide; (2 [R—(R,R)].

In-111-Octreotide Labeling Kit and Technique

A kit for the preparation of In-111-Octreotide is produced byMallinckrodt (OcteoScan™). The kit comprises a lyophilized mixture of:

-   -   10 μg octreotide;    -   2 mg gentisic acid (2,5-dihydroxybenzoic acid);    -   4.9 mg trisodium citrate, anhydrous;    -   0.37 mg citric acid, anhydrous; and    -   10 mg inositol.

Standard-Dose Example

For neuroendocrine tumor imaging a standard dose of 6 mCi is used.

Low-Dose Example

For neuroendocrine tumor imaging, a low dose of 0.6 mCi, about a tenthof the standard-dose may be used.

K: Indium-111-capromab Pendetide

Indium-111-capromab pendetide is used for diagnosis of prostaticcarcinoma and intra-pelvic metastases.

Capromab is a murine monoclonal antibody of the immunoglobulin subclassIgG-1-K, which localizes or binds specifically to a prostate-specificmembrane glycoprotein (PSMA) that is only expressed by prostaticepithelial cells (benign and malignant). The monoclonal antibody issite-specifically labeled with indium In-111-chloride using thelinker-chelator, glycyl-tyrosyl-(N,epsilon-diethylenetriaminepentaaceticacid)-lysine hydrochloride or GYK-DTPA-HCl. The resultant radiolabeledmonoclonal antibody conjugate, In111-capromab pendetide (CYT-356),retains the immunoreactivity of the unconjugated monoclonal antibody.

Following intravenous administration, In-111-capromab pendetidelocalizes to the prostate and some primary and metastatic tumor sites.Some non-antigen-dependent localization occurs, probably secondary tocatabolism, in normal liver, spleen, and bone marrow. In someindividuals, some radioactivity may localize in the bowel, blood pool,kidneys, urinary bladder, and genitalia

Indium-111-capromab Pendetide Labeling Kit and Technique

A kit for the preparation of In-111-capromab-pendetide is produced byCytogen (ProstaScint™). The kit contains a vial of 0.5 mg of capromabpendetide in 1 ml of sodium phosphate buffered saline solution adjustedto pH 6, and a vial of sodium acetate buffer containing 82 mg of sodiumacetate in 2 ml of water for injection adjusted to pH 5-7 with glacialacetic acid. The sodium acetate solution must be added to theIn-111-chloride solution to buffer it prior to radiolabeling.

Standard-Dose Example

For prostate metastasis imaging a standard dose of 5 mCi is used.

Low-Dose Example

For prostate metastasis imaging, a low dose of 0.5 mCi, about a tenth ofthe standard-dose may be used.

M: Indium-111-Labeled White Blood Cells (WBCs)

WBC scanning is a diagnostic technique that utilises the naturalmigratory behaviour of WBCs to provide an image of their localisation.By identifying the sites of infection and inflammation to which WBCsnaturally migrate, the presence and extent of active disease isrevealed. The patient's own WBCs (mixed leucocytes—granulocytes,lymphocytes and monocytes) are isolated from a sample of whole blood andare then radiolabelled with In-111. The radiolabelled WBCs are thenreinjected into the patient.

Section IV: Iodine-123-Labeled Radiopharmaceuticals

M. I-123-mIBG

I-123-meta-iodobenzylguanidine (mIBG) is used for diagnostic imaging ofthe adrenal medulla, for the evaluation and localization of intra- andextra-adrenal pheochromocytomas, paragangliomas, and neuroblastomas, aswell as for localization of metastatic lesions from these tumors.

In adrenergic nerves, guanidines are believed to share the sametransport pathway as norepinephrine and to accumulate in, and displacenorepinephrine from, intraneuronal storage granules. The retention of123 I- and 131-I-mIBG in the adrenal medulla may be a result of theiruptake in adrenergic neurons and subsequent sequestration intochromaffin storage granules. Due to their selective uptake mechanism,123 I- and 131-I-mIBG allow specific detection and localization ofneuroendocrine tumors and adrenal medullary hyperplasia.

After intravenous administration, there is rapid uptake of mIBG mainlyin the liver, and in lesser amounts in the lungs, heart, spleen, andsalivary glands. Although the uptake in normal adrenal glands is verylow, hyperplastic adrenals and tumors such as pheochromocytoma,neuroblastoma, and other tumors with neurosecretory granules have arelatively higher uptake.

Automatic Transfer of Information

Different devices associated with producing, shipping, preparing,administering, identifying radiopharmaceuticals and imaging, analyzingand diagnosing patients administered with radiopharmaceuticals,including, but not limited to, the various devices described herein,such as syringe, pump, IV line, mixer, camera, patient tag, ERP,dispensers, vials and/or pharmaceutical label may include a transceiveror other mechanisms for automatic reception/delivery of data and forstoring, analyzing and/or processing, e.g., comparing, data associatedwith a given radiopharmaceutical, procedure, protocol, producer, patientID, prescription, source, planned protocol, actual protocol and thelike.

Hence, the present invention relates also to a method of automaticcommunication of data related to a radiopharmaceutical or a patientadministered therewith among devices used therewith.

CONCLUDING REMARKS

The present invention embodies many aspects and embodiments, each havingmany sub embodiments and alternatives, the aspects and embodimentsinclude, but not limited to, radioimaging cameras with unprecedentedhigh resolution, algorithms operable in conjunction with the cameras,low dose radiopharmaceuticals, combinations of radiopharmaceuticalseither as compositions and/or kits, administering devices which mayinclude syringes, pumps and IV lines, mixers for mixing differentradiopharmaceuticals, an ERP system for controlling and monitoring eachone or more of these aspects and embodiments and their sub embodimentsand alternatives and diagnostic methods in which one or more of theabove aspects and embodiments and/or their sub embodiments andalternatives are used. Each of the aspects and embodiments of thepresent invention and/or each of their sub embodiments and alternativesmay be practiced in itself or in combination with other aspects andembodiments of the present invention and/or each of their subembodiments and alternatives. Hence, the present invention encompassesas novel and inventive concepts all combinations and sub combinations ofeach of these embodiments and aspects of the invention as well ascombinations and sub combinations of each of the sub embodiments andalternatives of any of these embodiments and aspects of the inventionand this application should be read as if each such combination and/orsub combination of each of the embodiments and aspects of the inventionand/or their sub embodiments and alternatives is described inparticular.

Thus, it is appreciated that certain features of the invention, whichare, for clarity, described in the context of separate embodiments, mayalso be provided in combination in a single embodiment. Conversely,various features of the invention, which are, for brevity, described inthe context of a single embodiment, may also be provided separately orin any suitable sub combination.

As used herein the terms “about” and “substantially” refer to ±20%.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention.

It is expected that during the life of this patent many relevantradioactive-emission-camera systems, cameras and methods will bedeveloped and the scope of these terms is intended to include all suchnew technologies a priori.

What is claimed is:
 1. A method of radioactive-emission-measurement,comprising: providing a SPECT camera for the detection of singleemissions, which camera having a region of interest having a volume ofat least 5×5×5 cm and a side closer to said region of interest;arranging said camera so that said region of interest coincides with ahuman body; imaging the region of interest from different orientations,using at least three detecting blocks each arranged to view said regionof interest at a different orientation from others of said blocks,wherein said imaging comprises detecting at least 1 of every 5000photons emitted from at least one radioactive-emission source locatedwithin said region-of-interest volume, through a collimator positionedin front of at least one pixel of each of the detecting blocks therebyblocking gamma and beta radiation and defining a viewing angle of atleast 0.005 steradians; and reconstructing a SPECT volumetricradioactive-emission image from said detected photons at a resolution of7 mm Full Width Half Maximum (FWHM) or better, said resolution definedunder conditions of irradiation by a substantially line source ofradioactive emission, with an activity of 5 mCi, within saidregion-of-interest volume, at a distance of at least 100 mm from saidside.
 2. The method of claim 1, wherein said imaging comprises detectingat least 1 of every 4000 photons emitted from the region-of-interestvolume.
 3. The method of claim 1, wherein said imaging comprisesdetecting at least 1 of every 3000 photons emitted from theregion-of-interest volume.
 4. The method of claim 1, wherein saidimaging comprises detecting at least 1 of every 2000 photons emittedfrom the region-of-interest volume.
 5. The method of claim 1, whereinsaid imaging comprises detecting at least 1 of every 1000 photonsemitted from the region-of-interest volume.
 6. The method of claim 1,wherein said imaging comprises detecting at least 1 of every 500 photonsemitted from the region-of-interest volume.
 7. The method of claim 1,wherein said imaging comprises detecting at least 1 of every 200 photonsemitted from the region-of-interest volume.
 8. The method of claim 1,wherein said imaging comprises detecting at least 1 of every 100 photonsemitted from the region-of-interest volume.
 9. The method of claim 1,wherein said reconstructing comprises reconstructing at a resolution,which is better than 6 mm Full Width Half Maximum (FWHM).
 10. The methodof claim 1, wherein said reconstructing comprises reconstructing at aresolution, which is better than 5 mm Full Width Half Maximum (FWHM).11. The method of claim 1, wherein said reconstructing comprisesreconstructing of a volumetric image having a line spread function,which is better than 4 mm Full Width Half Maximum (FWHM).
 12. The methodof claim 1, wherein said reconstructing comprises reconstructing at aresolution, which is better than 3 mm Full Width Half Maximum (FWHM).13. The method of claim 1, wherein said reconstructing comprisesreconstructing at a resolution, which is better than 2 mm Full WidthHalf Maximum (FWHM).
 14. The method of claim 1, wherein saidreconstructing comprises reconstructing at a resolution which is betterthan 1 mm Full Width Half Maximum (FWHM).
 15. The method of claim 1,wherein when the line source has an activity of 5 mCi, said detectingcomprises acquiring 10 million photons emitted from the line source, inless than 60 seconds.
 16. The method of claim 1, wherein when the linesource has an activity of 5 mCi, said detecting comprises acquiring 10million photons emitted from the line source, in less than 50 seconds.17. The method of claim 1, wherein when the line source has an activityof 5 mCi, said detecting comprises acquiring 10 million photons emittedfrom the line source, in less than 40 seconds.
 18. The method of claim1, wherein when the line source has an activity of 5 mCi, said detectingcomprises acquiring 10 million photons emitted from the line source, inless than 30 seconds.
 19. The method of claim 1, wherein the volumetricradioactive-emission image is a three-dimensional image.
 20. The methodof claim 19, wherein given a substantially uniform radioactive-emissioncylindrical source of 10 cm in diameter, as the region-of-interestvolume, positioned substantially at a center of viewing of the camera,the reconstructed image has an intensity variation of no more than about30%, so as to be substantially artifact free.
 21. The method of claim19, wherein given a substantially uniform radioactive-emissioncylindrical source of 10 cm in diameter, as the region-of-interestvolume, positioned substantially at a center of viewing of the camera,the reconstructed image has an intensity variation of no more than about20%, so as to be substantially artifact free.
 22. The method of claim19, wherein given a substantially uniform radioactive-emissioncylindrical source of 10 cm in diameter, as the region-of-interestvolume, positioned substantially at a center of viewing of the camera,the reconstructed image has an intensity variation of no more than about10%, so as to be substantially artifact free.
 23. The method of claim19, wherein given a substantially uniform radioactive-emissioncylindrical source of 10 cm in diameter, as the region-of-interestvolume, positioned substantially at a center of viewing of the camera,the reconstructed image has an intensity variation of no more than about5%, so as to be substantially artifact free.
 24. The method of claim 1,wherein: wherein said at least one detecting unit has a freedom ofmotion in at least one direction with respect to another of saiddetecting units, wherein at each position and orientation of thedetecting unit, the detecting unit defines a view; and comprising:determining a probability that a photon emitted at a voxel, centered atan x;y;z position, in a volume, relative to the camera for the detectionof single emissions, will be detected by the detecting unit, at a givenview; providing a first algorithm for choosing a plurality of views, forthe detecting unit; moving the detecting unit to positions associatedwith the plurality of views and obtainingradioactive-emission-measurements at the positions; and providing asecond algorithm for reconstructing a volumetric radiation distribution,within the volume, from the radioactive-emission-measurements at thepositions.
 25. The method of claim 24, wherein said camera is tailoredto a body structure, and optimized with respect to functionalinformation gained about the body structure provided by saidreconstructing, wherein the method further includes: modeling thebody-structure, based on its geometry; modeling anatomical constraints,which limit accessibility to the body structure; obtaining a collectionof views of the modeled body-structure, within the modeled anatomicalconstraints; providing a scoring function, by which any set of at leastone view, from the collection of views, is scorable with a score thatrates the functional information obtained from the modeled bodystructure, by the set; forming sets of views from the collection ofviews and scoring them, with the scoring function; and selecting one ofthe sets of views, from the collection of views, based on its score, asa predefined set of views.
 26. The method of claim 25, wherein thescoring function is based on an information theoretic measure ofuniformity.
 27. The method of claim 25, wherein the modeling thebody-structure includes modeling a radiation emission densitydistribution to form at least one region of interest.
 28. The method ofclaim 27, wherein the scoring function is based on an informationtheoretic measure of reliability.
 29. The method of claim 28, wherein:the modeling the body-structure comprises providing a plurality ofmodels of substantially identical volumes, but different regions ofinterest, the forming sets of views from the collection of views andscoring them, comprises forming substantially identical sets of viewsfor all the models and scoring the sets with respect to each model,based on the information theoretic measure of reliability; the selectingone of the sets of views, based on its score, comprises selecting basedon the average score for the plurality of models.
 30. The method ofclaim 27, wherein: the modeling the body-structure comprises providing apair of models of substantially identical volumes, but different regionsof interest, wherein the difference between the regions of interest isdefined by at least one delta; the scoring function is based on aninformation theoretic measure of separability; the forming the sets ofviews from the collection of views and scoring them, comprises formingsubstantially identical sets of views for the pair of models and scoringthe sets with respect to the pair; and the selecting one of the sets ofviews, based on its score, comprises selecting based on the score forthe pair.
 31. The method of claim 27, wherein: the modeling thebody-structure comprises providing a plurality of pairs of models ofsubstantially identical volumes, but different regions of interest,wherein the difference between the regions of interest for each pair isdefined by at least one delta; the scoring function is based on aninformation theoretic measure of separability; the forming the sets ofviews from the collection of views and scoring them, comprises formingsubstantially identical sets of views for the plurality of pairs ofmodels and scoring the sets with respect to each of the pairs; and theselecting one of the sets of views, based on its score, comprisesselecting based on an average score for the plurality of pairs.
 32. Themethod of claim 25, wherein: the modeling the body-structure comprisesproviding at least one model of no radiation emission densitydistribution and at least two models of different radiation emissiondensity distributions, so as to form different regions of interest forthose two models; and the providing the scoring function comprisesproviding a scoring function as a combination of uniformity,separability and reliability.
 33. The method of claim 25, wherein theforming sets of views from the collection of views and scoring them,with the scoring function, includes using the Greedy construction. 34.The method of claim 25, wherein each view of the collection of views isdetermined for a given detecting unit, by at least one parameterselected from the group consisting of a location, an orientation, apharmaceutical, a duration of measurement, and a time elapsed form theadministration of the pharmaceutical.
 35. The method of claim 25,wherein each view of the collection of views is determined at least byone detecting-unit parameter selected from the group consisting of adetector's material, a detector's thickness, a collimator's collectionangle, and a diameter of the detecting unit.
 36. The method of claim 25,wherein the obtaining the collection of views comprises computing thegroup of probabilities which form each view, analytically.
 37. Themethod of claim 25, wherein the obtaining the collection of viewscomprises obtaining the group of probabilities which form each view, bycomputer simulations, based on the model of the body structure and theview parameters.
 38. The method of claim 25, wherein the obtaining thecollection of views comprises obtaining the group of probabilities whichform each view, by measurements of a substantially point source fromdifferent locations and orientations, by a detecting unit.
 39. Themethod of claim 25, wherein the obtaining the collection of viewscomprises obtaining the group of probabilities which form each view, bymeasurements of a physical model of the body structure, embedded with anemission source, from different locations and orientations, by adetecting unit.
 40. The method of claim 25, wherein the body structureis selected from the group consisting of a prostate, a heart, a brain, abreast, a uterus, an ovary, a liver, a kidney, a stomach, a colon, asmall intestine, an oral cavity, a throat, a gland, a lymph node, theskin, another body organ, a limb, a bone, another part of the body, anda whole body.
 41. The method of claim 25, wherein the body structure isselected from the group consisting of a human body structure and ananimal body structure.
 42. The method of claim 25, wherein the modelingthe body-structure comprises modeling based on at least one factorselected from the group consisting of age, sex, weight and body type.43. A method according to claim 1, wherein said camera is aradioactive-emission camera, for radioactive-emission imaging withoutcoincidence, the camera being designed and constructed having highsensitivity selected from a group consisting of: (a) sensitivity interms of speed of data collection and spatial resolution, at least asgood as a gold standard for PET imaging for at rest myocardial perfusionwith N-13-ammonia (NH₃), at a dose of 740 MBq with attenuationcorrection; (b) sensitivity sufficient for reconstructing an image undera Cobalt wire Nema test of a line source of 5 mCi cobalt with a linespread function of less than 7 mm Full Width Half Maximum (FWHM) throughair at a distance of at least 100 mm; (c) sensitivity sufficient forresolving through air at a distance of at least 100 mm under a Nema BarPhantom test of gaps formed between 1 mm wide led bars positioned lessthan 7 mm apart from one another over a uniform cobalt disc; (d)sensitivity operative for image acquisition of a full organ in less than10 seconds at a spatial resolution, capable of identifying objects notgreater than about 7 mm×7 mm×7 mm with a signal-to-noise ratio of atleast 4 to 1 or better; and/or (e) sensitivity allowing acquisition ofat least 1 out of every 5000 emitted photons while allowing areconstructions of a 3D image with a resolution of not more than 5 mmand energy resolution of not more than 15%.
 44. The method of claim 43,wherein said sensitivity of said camera is selected to be at least 2fold that of said gold standard for PET imaging.
 45. A method accordingto claim 43, wherein said sensitivity allows acquisition of at least 1out of every 5000 emitted photons while allowing a reconstruction of a3D image with a resolution of 5 mm or better and energy resolution of15% or better.
 46. A method according to claim 1, comprising providingTeboroxime-Tc99m into said body and wherein said reconstructingcomprises reconstructing a distribution of said Teboroxime-Tc99m in saidregion of interest.
 47. A method according to claim 1, wherein saidcamera has a geometry which aligns said region of interest with saiddetectors and collimation thereof so that at least 1 in 5000 photonsfrom said region of interest is absorbed by the detectors.
 48. Themethod of claim 43, wherein said sensitivity of said camera is selectedto be at least 5 fold that of said gold standard for PET imaging. 49.The method of claim 43, wherein said sensitivity of said camera isselected to be at least 10 fold that of said gold standard for PETimaging.
 50. The method of claim 43, wherein said sensitivity of saidcamera is selected from a group consisting of: sufficient forreconstructing an image under a Cobalt wire Nema test of said linesource of 5 mCi cobalt with a line spread function of less than 6 mmFull Width Half Maximum (FWHM) through air at said distance of at least100 mm; sufficient for resolving through air at said distance of atleast 100 mm under a Nema Bar Phantom test of gaps formed between 1 mmwide Lead bars positioned less than 6 mm apart from one another over auniform cobalt disc; and operative for image acquisition of said fullorgan in less than 10 seconds at said spatial resolution, capable ofidentifying objects not greater than about 6 mm×6 mm×6 mm with saidsignal-to-noise ratio of at least 4 to 1 or better.
 51. The method ofclaim 43, wherein said sensitivity of said camera is selected from agroup consisting of: sufficient for reconstructing an image under aCobalt wire Nema test of said line source of 5 mCi cobalt with a linespread function of less than 4 mm Full Width Half Maximum (FWHM) throughair at said distance of at least 100 mm; sufficient for resolvingthrough air at said distance of at least 100 mm under a Nema Bar Phantomtest of gaps formed between 1 mm wide Lead bars positioned less than 3mm apart from one another over a uniform cobalt disc; and operative forimage acquisition of said full organ in less than 10 seconds at saidspatial resolution, capable of identifying objects not greater thanabout 2 mm×2 mm×2 mm with said signal-to-noise ratio of at least 4 to 1or better.
 52. The method of claim 43, wherein said sensitivity of saidcamera is selected from a group consisting of: sufficient forreconstructing an image under a Cobalt wire Nema test of said linesource of 5 mCi cobalt with a line spread function of about 1 mm FullWidth Half Maximum (FWHM) through air at said distance of at least 100mm; sufficient for resolving through air at said distance of at least100 mm under a Nema Bar Phantom test of gaps formed between 1 mm wideled bars positioned less than 0.1 mm apart from one another over auniform cobalt disc; and operative for image acquisition of said fullorgan in less than 10 seconds at said spatial resolution, capable ofidentifying objects not greater than about 0.1 mm×0.1 mm×0.1 mm withsaid signal-to-noise ratio of at least 4 to 1 or better.
 53. A methodaccording to claim 1, wherein said viewing angle is at least 001steradians.
 54. A method according to claim 1, wherein said plurality ofblocks comprises at least ten blocks with different viewing lines ofsight.
 55. A method according to claim 54, wherein each of saidplurality of blocks is independently movable.
 56. A method according toclaim 1, wherein each block contains at least two detecting units.
 57. Amethod according to claim 1, wherein said arranging comprising arrangingsaid detecting units and said body in close proximity to each other. 58.A method according to claim 1, wherein said detecting units are locatedwithin a housing which does not move during said detection of singleemissions.
 59. A method according to claim 1, wherein said collimateddetectors use non-parallel collimation.
 60. A method according to claim1, wherein said at least one collimator comprises and adjuster to adjustsaid viewing angle.
 61. A method according to claim 1, wherein said atleast one collimator as is a wide angle collimator having an angle widerthan 90°.
 62. A method according to claim 1, wherein each saidcollimator is positioned to collimate radiation in front of multiplepixels of a detector.
 63. A method according to claim 1, wherein eachsaid collimator is positioned to collimate radiation in front of asingle-pixel detector.
 64. A method according to claim 1, wherein saidat least one collimator is a narrow angle collimator having an anglenarrower than 90°.
 65. A radioactive-emission-measurement system,comprising: a camera for the detection of single emissions having atleast three detecting blocks, the camera having a geometry such thatsaid at least three detecting blocks detects at least 1 of every 5000photons, emitted from at least one radioactive-emission source, locatedwithin a region-of-interest volume of at least 5×5×5 cm, wherein eachsaid detecting block comprising one or more collimated solid-stateionizing radiation detecting units, each detecting unit including atleast one pixel, each said detecting block has at least one collimatorpositioned in front of said at least one pixel, said at least onecollimator substantially blocks gamma and beta radiation and defines aviewing angle of at least 0.005 steradians, said detecting blocks havingdifferent lines of sight and arranged to view said region of interest ata different orientation from others of said blocks; and adata-processing system, configured for reconstructing aradioactive-emission SPECT image from detected photons under a Cobaltwire Nema test, said radioactive-emission SPECT image having a voxelsize of 7 mm or less.